The system you took off is a good choice to tune for new engine. Can also be adapted for MPFI. Cost of tuning equiptment needed about $150. plus your time
The Vortec Spider is OK but not great and any 1996 and newer OBDII is much more expensive for software to tune with. Your actually going backwards. Can get a Vortec timing cover for sensor although I'm not sure the crank will accept the toothed wheel needed.
Common conversion for all 97 to 00 Vortec engine controllers is 0411 PCM from a LSx engine, this is way to go. But still $900 for EFI Live...