4WD to RWD conversion

[4Elatemodel]

The truck is a 1968 short bed stepside if that would clear anything up. I was originally planning to do a full ride tech kit but the application i was looking for was a street/race truck something i could do a bit of it all in but mostly just terrorizing my neighbor hood and taking it to a road course to run around.I am open to other suggestions though. As for engine and trans i thought about it but havent nailed it down because of not actually possesing the truck. Some intial thoughts were ls of somekind, 383 carb,383 fuel injected but really my goal is a hp window of about 500-600 hp. Thanks again your being super helpful!