It would probably be cheapest and easiest to buy a series III that's already been converted, or even get an original 90/110 V8. Never done it myself, but from talking to people who have and looking at converted vehicles:
- Welding would be needed to modify the bulkhead and rig up an exhaust system, and no doubt to make up various brackets and plumbing adaptors.
- You'd need a adaptor plate to mate the engine to the box
- unless your'e really good, you'd need to buy some engine mounts.
- I've got a feeling that a remote oil filter conversion is needed.
- You'll need to buy an electric fan too - not cheap for a decent one.
- The engine will go in without moving the front panel
- Standard radiator is probably a bit iffy with a V8