I don't know the definitive answer to your question, but I bought a recalibrated autometer shiftlight and the pills didn't match the indicated RPM (about 700 RPM difference between pill and tach reading). There's nothing wrong with my tach.
So I did just as you suggested and increased the pill number until I got to the actual RPM that I wanted the light to go off at. This has worked for me. One problem you might have with a unit that is not calibrated is you may find it impossible to get a pill that will work at the RPM you need.
I recommend calling Autolite tech support.
By the way, how's it going up there in Laytonsville?
So I did just as you suggested and increased the pill number until I got to the actual RPM that I wanted the light to go off at. This has worked for me. One problem you might have with a unit that is not calibrated is you may find it impossible to get a pill that will work at the RPM you need.
I recommend calling Autolite tech support.
By the way, how's it going up there in Laytonsville?