That engine had 10.5 or 10.6 as was stated in compression and really good flowing heads with larger valves as was stated and the tight LSA put it into ping mode.
Some attention to details when building a high cylinder pressure engine.
NO sharp edges anywhere in the combustion space and NO stickups like casting flash allowed in the combustion space.
Smooth intake runners are a poor choice as they do not keep fuel atomized as well as a very rough intake runner texture.
The little things can make or break a build. There may have been some missed attention on that build.
I built a .030 over 396 years ago for a friend and it has 11:1 compression, a comp 280H that was made using the SBC masters so .544" lift and 234 at .050 duration. I had it ground on a 108LSA.
210-215 psi cranking pressure, it runs excellent with open chamber oval port heads from 1969, I ported those heads, they have 2.19-1.88 valves.
It has been together over 15 years and gets hammered on.
91 Octane from 7-11.
38 total timing. all in by 2200rpm. 4200lb truck with 3.08 gears currently. limited slip that usually has 1 tire hooking.
He had it in a 1969 3/4 ton for a few years and pulled his trailer and tractor with it.
Then a Moore Ok tornado stuck the house on top of the truck.
Engine is now in a 1/2 ton 1966 truck that is just as heavy.