The wording of your question was a little confusing to me at first. If I understand correctly you have “two” Broncos; one daily and one off road. One thing I should mention right off the bat is that you may have a good set of heads on that 351w. It has been long known that one of the best heads ever to be on a 351w was in 1969. This head also spilled over to 1970, but not the whole production year. The part number for this head is (C90Z-6049-F). If you have this head I recommend you keep it with the 351w. Not only will it work better then the GT it will also save you a lot of money. When you mix and match a pre-’77 make heads there is a little work involved. It is minimal but it does add up. Immediate differences are water jackets as well as the bolt size. There are some kits out there to work out these bugs, but I think you’ll be happier if you leave it alone; save your money to recondition the 351w heads. Your GTs will work nice with the 302 and they will help with the infamous “bronchitis” on almost all Ford heads. As far as your ’73 302s go, although they vary, they are probably a 63.2cc. As far as the cam is concerned it does not make your heads breath better. You could have a great cam but it is worthless if you have bad heads. The quicker and more air an engine can take in will always produce power. In fact, anything you do to make your engine breath better will produce more power. One of the biggest problems Ford engines have is the head. If you solve this problem or even somewhat correct it you will have a motor to be reckoned with. There are many cams out there so to say which ones are the best is difficult. I personally favor the Comp Cams extreme series for 4x4s, but you need to do the math to find what you are looking for—every situation is different, daily driving, wheeling, towing, and the quarter mile are only a few examples of uses. Don’t fall for “one size fits all”, that’s the factories philosophy.
One more tip, don’t ever even consider using a post-’77 351w head! They say Ford has a better idea but not when it comes to what they did to the poor 351w in the late 70’s and 80’s. The 351w I’m running is an ’84 block and the factory set-up almost made me sick. The heads on my block were 79cc, and Ford didn’t stop there but felt a “dish” piston would complement this arrangement. The legendary 351w was now lucky if it had a 7 compression ratio.
I hope this helps some,
Happy Trails
Shuby
