This thread is intended to provide a checklist of parts needed and point you to a write-up on how to convert an Early Bronco equipped with the stock inline 6 to a small block V8.
First, A Word Of Advice
Basically, this project involves eliminating everything forward of the transfer case and replacing it with V8 specific parts. Do your homework in advance and don't begin the conversion process until you have ALL the parts required. Otherwise you run the risk of stalling out on your project due to confusion, lack of funds, time scrounging for parts, or just life in general getting in the way. With the all necessary parts acquired and a good gameplan in place, this process can go quickly and minimize the amount of downtime for your Bronco. If only I'd done this, I could have at least still been enjoying a slow 6 cylinder Bronco instead of no Bronco at all for a long time. I now adhere to this principle when undertaking any moderately sized or above project.
Checklist of Needed Parts
Small Block Ford V8- Keep in mind there are no engine parts that are interchangeable from 6 cylinder to V8. You are going to need a V8 complete with intake, carb or EFI, air cleaner, exhaust, fuel pump, fuel lines, ignition, plug wires, starter, water pump and timing cover, accessory brackets (ok, you can re-use the alternator, and A/C or power steering if you have), pulleys, belts and if applicable, bell housing, clutch disc, pressure plate and motor plate. I'm sure I've left something off. The easiest swap is an engine directly from an Early Bronco as it should already be set-up with the appropriate water pump, timing cover, and pulleys. 5.0s and 5.8s can be installed, but may require further ingenuity to make clearance between the front dress of the engine and the radiator. In my opinion, the Explorer 5.0s make the best candidates for V8 conversion because of their short style water pump and timing cover.
Transmission- don't even think about using that stock 6 cylinder tranny
Tramission Adapter (aka Intermediate Housing)
Transmission Output Shaft (aka Spud Shaft)
There are numerous options here depending on your desires and budget. I was able to get the above transmisson pieces as one unit free of charge from a great member on this board. People are always upgrading so check the For Sale or Free Parts section in the Classifieds and you might get lucky like I did.
V8 Clutch Fork
Clutch Linkage- 3 pieces here, if you're swapping in a 5.0 you're also going to need a EFI clutch equalizer bracket (Wild Horses) so that the equalizer bracket has a place to mount to the engine
Motor Towers (Frame Brackets)
Motor Mounts- standard or extreme duty available
Radiator- the smaller 6 cylinder rad will not adequately cool the V8
Radiator Hangers- because the V8 radiator mounts completely different than the I6 radiator
Upper Radiator Hose
Lower Radiator Hose
Throttle Linkage - instead of going with the stock Bronco linkage, you can instead choose a simpler, better looking throttle cable available from BC Broncos or Summit Racing
The Actual Conversion Process
This link will provide an awesome write-up on the how-to process and is very comprehensive. http://www.lonestar-ebc.com/Tech/TechItem.asp?TechID=19
I don't want to be repetitive of his great write-up and I don't think there's anything I'd add to it aside from the above mentioned throttle cable option versus the stock throttle linkage.
If you have anything to add to this post, feel free to add below.
Additional Sources: Tom's Bronco Parts catalog, Wild Horses catalog