I haven’t checked initial timing since my 1972 Cutlass back in the 1980’s. Everything is in before 1100 rpm and total time that sucker. Non locked out distributor.
We put my distributor on Tim's machine and put a great curve in it, we did timing sweeps after the engine was broken it, so we've been very close to the higher rpm all in timing (5500) based off our initial, another benefit of having a dyno.
My msd box retards the timing a few degrees up in the rpm range