I think tow big point's that needs to be looked in to or timing and compression or as my dad wood say hot and hotter.
#1
Timing the stock V1 timing mark is at 23 deg BDC.
It kind of works like this The carb is a flame thrower .
The more time you give the flame it the hotter things/cylinder/head get.
We have no vacuum advance to adjust timing with or BIG flame throwers giving less flame/heat timing at WOT.
So in part we need to set or timing for WOT .
So by reducing flame burn time in the combustion chamber we reduce BTU/heat transfer to cylinder/head.
Thar or three ways to do this.
The biggest is spark timing try like 18deg's BTDC.
Next wood be Ex system back presser.
last exhaust port timing give it more timing up it 5 or 10 deg's.
And the bones is by dumping more flame in to Ex system.
The exhaust chamber loves it hot.
As RPM's go UP and UP it gets hotter and hotter
As it gets hotter presser goes up .
More heat and presser make shock waves move faster moving the power band up in RPM's at the same time = more power.
#2
The higher the compression makes all hotter .
Compression you don't need HI Compression with a well tuned EX system ports and carb.
A good EX system will supercharge/raise compression by over stuffing the combustion chamber.
10 or even 9 to 1 shod be fine.
Bat back