My choice would be the inline 292 motor, bolts up to all the V8 tranys, lots of power and easy to get parts for. My limited experience with GMCs while a great motor the heads on most are cracked and hard to find.

Best of luck


It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed