carbureted 5.7 - 6.1

I think the big question is what sort of power are you looking to get out of it. The 5.7 seems pretty stout from the factory, but like ram mentioned some years have had issues with valve springs. If you're going to hop one up some with a cam and stuff you'd probably end up swapping out the springs anyway, so that might not be a huge issue. I think I've heard the bottom end is good for around 500 hp stock on the 5.7.