V8s require a lot of body work. Have a look in the engine bay of one in Billing and you will see what the problems are. It's not just the engine size but a complete suspension redesign. I'm thinking now of an XE with Kawasaki ZZR 1100 carbs. Kits are available. Getrag 240 5 speed box which will handle up to 180bhp, uprate the drive shaft, LSD and up the brakes.
All of this and more will take considerably more time that it took to write this and a lot more difficult.