Ok, just tested the compression cold, wide open throttle, cold engine, elevation 5200ft asl. The result was 103 psi.
I get the noise, which is most similar to the noise in the GussGuss video, when hot or cold, low RPM pulling a hill. The noise is reduced when opening throttle and increasing RPM. I will try to get a video or sound recording.
Okay, at 5200 ft elevation, you probably are not going to get pinging, and especially not with 103 psi compression. Unless the engine is overheating for some reason. So, that's most likely okay.
The sound that I am hearing on the Guss Guss video sounds like it could be a bearing.It probably wouldn't hurt to pull the head and barrel to check out the con rod for up/down play, also noting if there is any play whether it is coming from the big end, or perhaps the main bearings.
It's fairly easy to do that for an internal test. Probably be apart and back together in an afternoon.
Guss Guss needs to also do a compression check, because if there is a high compression piston in there with no spacer under the barrel, and it still has the stock cams in the normal timing position, then it is probably too high compression if it is anywhere near sea level elevation.