WOW This is a very nice truck.
I am doing what BIG CHEVY 3600 talked about. I hope it lives up to the bolter's scrutiny.
I am adding a SB400 / TH400 and doing the 12V thing to my 3800, but trying to keep the look (outside) stock.
You will also need to add engine and transmission supports on the frame if you venture down a traditional SB V8 path - they can be readily purchased.
Good luck and enjoy your truck whichever choice you make.
