Are the TBI flow ratings wrong, or was a different pressure spec'ed for engineering when setting up the calibrations? Did GM / Delco flow them using gasoline or another fluid, such as Stoddard Fluid? This same road was travelled 15 years ago and IIRC injectors were checked. Final decision for me was to work out the flow rating from the calibration. I do as previously mentioned and scale the value whenever I can.

All I'm going to say about the math right now is this:
Picking different numbers to make the math work just isn't fair. Maybe Robert can chime in and give us the application that engine / cal is from and I can try with Delphi's published flow ratings.
No need to recalculate constant when AFR is a variable in the calibration.
It may be as simple as dividing constant by 3 or 4 but until I work out the whole equation I don't feel this has reached a conclusion. After all, the 7427 PFI conversion was supposed to be as simple as a jumper or two and a bit change but look how much effort's gone into straightening that one out.