WOW once I posted this I saw I had rambling along for quite some time. Sorry.
I started by putting an '87 MA 305 Firebird TPI on a 350 in a 51 truck in 1989 before you could even find pin out diagrams easily. I have fuel injected all of my old car projects since then and modified every new vehicle since then as well. Depending upon how good you are with wiring, you can simply get the A9 pin out diagram and trace everything back to the right pin in your harness. Even the batch fire can be fixed. Also dependant upon your individual skills it "might" be cheaper/easier to go that route or it will be FAR easier to just by a harness thats all base don you. If a pile of wires scares you go by a harness. For me I would pull the plug on my DA1 and make sure it fit my A9 and go.
However, why do you feel the A9 will be required. I have seen countless things on the internet about how if you make "any" mods the computer will not be able to run the engine. That simply isn't true. Just like you have to change the cam on an old 302 to the same firing order as the HO. NOT TRUE. There are some quirks but the SD computer when modifing the engine but it will often work through them. I have the original 71 302 in my bronco with the SD original firing order, RV cam, headers, and supersingle exhaust. When I got it it had a 4BB holley carb and a single plane high rise manifold. No doubt the builder had read Hot Rod Magazine and not 4WD.
It ran like a bat out of hell (at least for a 302 in a bronco) but lacked low end torque and it was a real pain to drive offroad. You basically had to use the granny in the NP435 everytime you started off. I bought my SD system for an 87 Mustang on ebay for less than I sold the carb on ebay. The common wisdom was that the computer wouldn't run the engine. Well if you put the computer on it and started it and didn't keep messing with it you would believe the common wisdom, but once all the connections with high voltage drop across them were fixed, the bad brand new sensors were replaced, and the engine warmed up it ran like a top. The SD EFI gave me enough low end torque to where I rarely use the granny anymore and I gained top end as well.
I have had several modified speed density systems and what I have found is that the computewr tends to run the modifications just fine as long as you do not put a cam in there that decreases the vacuum signal at idle. An RV cam will ususally give you more vacuum, headers and other mods can alter that signal was well but the cam is the big issue. Dont know why you would want anything but a good ow end torque cam in a Bronco anyway. I feel no need to run over 85 and nearly every cam on the market these days will let your engine do that unless you have ultra low gearing in place to make up for the fact that you put the wrong cam in.
What does happen with all the altered SD systems I have dealt with is that the run cold functions of the computer are really out of whack and it might takes months for the computer to build tables to run you engine cold but it does eventually do it. Unfortunaetely if you disconnect the battery you get to start all over. I can hook my broncos computer up to a seperate battery if I have to disconnect the battery for some reason. You basically have to sit there in the truck and start it and let it die start it again over and over when ever you have the time. As you are doing this the engine warms up and once the computer gets out of cold start/run mode it will ususally be just fine unless you put in a lopey cam. I had my bronco to where I could walk out of my deer camp on a 15 degree morning turn the key and it would start and then I would go back in and get ready have some coffee and it would idle until it got warmed up. I had to replace the intake air sensor and I disconnected the computer from the battery so the computer could start from scracth. That was 6 months ago and I havent been driving it enough so I still have to resart it once or twice before it warms up, but it runs fine once warm and alos while driving cold, it just hasn't completely figured out how to idle COLD but I kinow it will eventually because it and others have before.
Ther is no doubt that the SD systems as Ford designed it has issues if you change the cam signal such that vacuum decreases (high lift LONG duration), it isn't a given that the SD computer will not be able to deal with an RV style cam that increases the vacuum system (high lift SHORT duration). My dad had a full size 351 that when he bought it had the catalytic converted removed headers, duals and an RV cam. THe smog pump had bee disconnected as well. It ran like a stripped a$$ ape. He however lived in a TX county that required pollution inspections and part of the deal was that the guy had to put everything back to stock (he had kept everything) He did and my father used it for 10 years and over 200K miles on it, but although it ran jsut fine it was not the power house it was before with those changes, and it used the exact same computer.
If I had the time I would figure out if they can how to make the Chevy distributor controls on thier TPI computer run the Ford SB. Reasons the 92 corvette computer is SD and water proof and heat resistant. It was designed to be placed in the engine compartment. It can be easily and cheaply altered by replceing the chip, it has a knock sensor so you get the most out of your engin depedant upon the fuel that is being used. The only draw back is that it is batch fired so it idles a little different than SFI but thats hardly noticeable. The beauty of it is the heat resistant, water proof computers are a dime a dozen becaus GM used them on 6s anf 4s and all you have to do is change the chip to run an 8. You call up a chip guy and tell him everything about you vehicle. CAM spec, gearing, wieght, displacement, they way you want to use it etc. and a week or so later the chip arrives you plug it in and never ever deal with alkl the extra crap that goes along with MA.
Just like the people that say you cant run the old firing order I believe that many of the so called reasons you cant do it come from other issues that are not being addresses like bad connections and sensors. My old engine with the old firing order idles better than any carb engine I have ever owned (since 1975) but it does not idle as good as the Mustngs where you cant even tell it running. But who cares It still even idles better that a Chevy TPI which is batch fired.
I firmly beive that many people try to use SD and give up due to bad connections, bad sensors or are simply put out by the cold start/run issues. Ford SD systems can not deal with longer duration cams than stock so the mustang crowd says you cant alter the engine. We tend to go the other way and shorten duration to get low end torque and the Ford system may be able to run that quite well. My theory when I did mine was these internet experts are often wrong I will give it a shot because I already have it, and its not gonna cost anymore for me to fix it change it later if I do not like it.
I will also add that I corrected a lot of idle issues by taking apart the 10 pin connectors on the mustang harness and soldering and shrink wrapping them. The engine went from a rough idle that almost had me convinced the MA guys or the firing order guy were right and I found out neither were.
