Russ, on the carbs where the part throttle cruise was in the low 12's, the motor was running smoothly enough where I don't think it would drive bad at all.

I've had quite a few years and plenty of examples to look at, and when they come off the dyno like this, and get put right into the car without getting the part throttle a/f ratios into a more favorable range....... The trend does seem to suggest that the instrumentation isn't lying.
Those motors end up getting abnormally poor fuel mileage, plugs that are always dark, and sometimes even gassy smelling oil.

I had a really mild 505 on the dyno about a week ago.
It had a Holley 850vs on it.
Jets 80/88, part throttle operation very crisp and clean in the low-14's, WOT in the 12's & 13's.
No tendancy to get "fat" at any throttle or load setting.
That carb was a good match for that motor.