your build sounds very similar to mine: 383, vortec heads, GMPP spread-bore (q-jet) manifold for vortec heads, TBI adapter plate, 46 mm TB, etc in a '91, 3/4 ton 4x4 burb. Only differences are cam and trans: I'm using a stock vortec L-31 cam (and the complete roller valve train that came with it) and my burb has a 4L80e. Tuning has definitely been a challenge for me. Lots of battles and trial and error, but the help on this site is awesome. Lots of knowledge and experience here. Almost four years later and I've finally gotten my tune 80% to where I want it and the truck is running the best it ever has in my eight years of owning it. I still am working on timing. I agree with Dave W - go with the vortec timing table to start out with. You won't be able to use my bin files directly since we have different trans, but perhaps my fuel tables will be of use to you. Let me know.

You may be able to benefit from reading about some of my problems in the last few years by searching threads I started. Make sure you read to the end!