As far as the harness goes, I'd suggest building your own...to fit the car perfectly, and look like it was made that way. It's not all that difficult, just time-consuming. The truck harnesses are EASY to find, and will have to have the injector pigtails swapped out to the LS1 style "EV1" connectors....and wires re-routed/re-pinned to fit how you want it to. Truth be told, even with a ls1 f-body harness, you're going to be tearing into it and deleting/re-routing wires for your specific application. F-body PCM's aren't too difficult to find either.
Keep in mind that your also going to need ls1 injectors,fuel rail, intake, and possible throttle body (depending on what your engine came with).