I'll chime in with my 2 cents to help out a new member (like I was not too long ago at all) and say that you're already heading in the right direction by ditching your old 5.7 and going with a 5.3....anywho, after completing my swap I had one regret and that was that I didn't put a cam in when I did the rebuild and to be honest my funds were stretched way too thin and the truck is my daily so I had to get the swap moving double time. If you can't afford a big flashy new cam and valvetrain setup that's totally fine because a used LS6 or LS2 cam will bolt right in with no other mods except the tune to match. Now, I put a LQ9 6.0 into my truck and it already has a decent amount of hp and torque especially with the longtubes and tune so I'm not necessarily missing out on any power but I'd like a little extra to put me over the 400 mark in torque considering I pull a '77 Airstream around and I need a little more on the bottom end especially for hills. If you do nothing else to your engine get a cam and any other LS6 parts your wallet can afford. Also, I almost forgot to mention that I bought an A/C relocation kit from Jeff (Lextech) and I'm extremely happy with the fit and quality of it, (well worth the purchase) so if you have the sanden style compressor, you should also get that kit. And when you pull the engine measure the distances between the flexplate and block on both the 5.3 and 5.7 to make sure you don't need the space/adapter because I didn't on my 6.0 but I heard it might be different on the 5.3