Saying that the ring-gaps are in spec is Not helpful.
My KB107s were installed with loose skirts and gaps in spec, and it still overheated and the in-spec gaps were the sole source of my overheat.
The timing curve was 14 initial/going to 28@2800/going to 34*@3400; with 22* in the VA.
Therefore TOTAL Cruise-Timing was and still is, 50*@2800, going to 56* at 3400
Furthermore;
When cruising, I throw in up to 6* more from my dash-mounted, dial-back, electronic timing module, or
The same module can retard the timing up to 9 degrees. and
the engine did not/has not, after the new gaps, overheated when retarded to as little as 5* ignition advance at idle.
All our SBMs; at idle/no load, will want far more advance than our distributors can give, and still run WOT. By 2000/no load, most will accept more than 45*.. By 2800 cruise, mine wants 50/55*
But
At WOT/full-load, and after ~3600, they all want ~34* +/- 2*.