I just completed this swap in my Firebird. I bought a drop out from a wrecked G8 GT that included the throttle pedal and wiring harness. Purchased a cam kit from Brian Tooley Racing - LS3 NA Stage II cam 225/238 .612"/.585" 113+3, Titanium retainers, dual valve springs, seals and Chromoly pushrods for $700 and some change. I had Mike Norris do a mail order tune on the ECU and the harness reworked by John at Modern Vintage Systems. John bench tested everything and I'm super happy with everything so far as it fired up on the first try.

Something to think about is the oil pump. I swapped mine out for a Melling unit. Some people run the stock one but others said to swap it out, said there may be oiling issues if not using the factory oil pan.