If you were able to find one the isuzu npr 4cyl turbo I had in my snap-on truck kicked a$$ and got good milage, gobbbs of torque. Not too much to do as far as computer stuff either. Almost any inline 6 has allot of torque, the jeep 4.0 kicks and you can get all kind of adapter plates for the trans.
good luck, post pics when its done.