did you have a chance to get a bit of break in on the rings? a few heat cycles? could be the end gap wasnt properly set on the rings or tolerances werent measured on the cylinders.
oem parts or aftermarkets? either way something is amiss with the top end if your comp tester is reliable along with the test procedure.
being that the pto side is further away from the fan, temps are usually higher on that side. but i have had phazers around here than ran fine at around 95 psi using my comp tester.
although you have been through the carbs, do all the circuits enter and exit using spray or air? i see it alot where someone thinks they have been all the way through, but actually missed a circuit.
next is the choke cable adjustments. thats a two into one cable, and its not uncommon for one side or the other to stretch or be mis adjusted.