Any Chevrolet engine will work fine, 6 cylnder, Small Block, Big Block, they'll all work, provided that you have the right bellhousing and engine mounts. For the transmission, you'll be looking at late model stuff for a 5 or 6 speed. You'll want to check out Advanced Adapters for a bellhousing with the correct bolt pattern. The NV4500 5 speed is a good choice, there was also a 6 speed used on the late GMT800 ('01-'07) trucks that should work, depending on what T-case you end up using as the weather they can be adapted. Again, check out Advanced.
