Check out those two links. Just from doing a quick browsing, it looks like some good info.. Looks like it's a pretty involved swap, but would probably be worth it in the end if done. If you don't want to go to that extent and keep the 5.7L, I'd look into the following...
New cap, rotor, wires, and spark plugs.
Spider injector kit.
New fuel filter.
Cold air intake.
Headers and muffler.
Performance camshaft and internals.