The injector data is set for vacuum-referenced IFR, but Offset is non-referenced.
What is the P/N of those 800cc Deka's? Got a link to where you purchased? Those are also known as Deka 80's, but there is a short and long version. Looks like you're using the AACorvette 80lb Long Deka IV data. Is that what you have installed?
Yeah it's the AACorvette Deka 80 Long data. What you need to do is go into the Offset table and copy the 0kPa column to the rest. Engine>Fuel>Transient>Min Fuel Mg to 0.010.
I'm also assuming by 0 vacuum you mean low manifold pressure and high vacuum. 0kPa vacuum is atmospheric pressure, or WOT without boost. The more vacuum the more error due to the Offset not being setup correctly. Not sure how this made it past the tuner with 20 yrs experience, but whatever. The Min Fuel setting is probably acting as a floor and not allowing short enough injector pulses to get fueling correct. Again, need to see Injector PW for both banks.
Injection timing would be a good thing to do. What are the complete specs, including ICL, for this Stage 4 cam?
See it's like I was saying. Injector data and MAP. Get the GM sensor per previous recommendations and adjust your injector data. Things will go a lot smoother.
Set P0101-P0103 to MIL on First Error instead of Second. Even with and SD OS you still have to manually set it to fail the MAF.
After all this see if you can get a good VE table going.