You'd need to use a Series II throttle body, fuel rail, and wiring harness/PCM. Injector connectors will probably be required for the new injectors, as well as a lot of PCM programming to make the engine function properly. You'd have a Series III engine, but have to run it with Series II electronics.
The tranny will require a 03+ PCM (you'd need to get one from an Impala/Monte with the 3.8L) because of internal electronic differences that came long in that year. I'd stick with 04-05 Impala/Monte PCMs just to be safe. Also, there are some tap-shift 4T65Es out there with Series III 3800s, so I'd be careful not to get one since it is different than the regular 4T65Es and might be incompatible.
If you really want to do this, I'd source the engine and tranny separately to avoid any incompatibility issues with the electronics.
