You are getting distributor advance and crankshaft advance all mixed up here.
Distributor advance figures are read directly off the distributor machine.
Crankshaft advance is the numbers that come off the crankshaft.
A stock Cruiser distributor that has centrifugal advance of 13 degrees @2000 distributor RPM will give a crankshaft advance reading of 26 degrees @ 4000RPM installed in the truck. This is way too much BTW.
Mike, on your DUI setup, it sure sounds like the tag is a mix of dist RPM and crank timing. 23 degrees of dist timing would yield 46 degrees of crank advance (waaay too much). But the timing should be all in at 2000distributor RPM. if timing is all in at 2200 crank rpm, that's way too early, 'cause the engine is still climbing the power and cylinder pressure curve. Anyway, I expect the performance distributor to give 23 degrees crankshaft advance at 4400RPM.
FWIW, the typical Toyota electronic distributor will read 12 degrees mechanical advance @ 1900 distributor RPM and 11 degrees of vac advance. This gives a total 23 degrees of distributor advance or 46 degrees crankshaft advance. This is why an FJ60 w/ a healthy engine and no smog equipment will rattle like crazy under load. We want a max total ignition timing of 34-38 degrees on the 81-87 engines, a few more degrees on the earlier low-compression engines. The way to achieve this is curve the distributor for 7 degrees vacuum, 21 degrees centrifugal and 9 degrees base. Max crankshaft advance is then 37 degrees.
This concludes today's lesson on the vagaries of distributor advance. If there are any questions, please see me when I have no class.