I read it the first time, I wouldn't have commented. As you pointed out. it doesn't make sense to open at the end of the compression/beginning of the power stroke. I am not exactly following your test procedures either and I went back and reread it a few times to try to follow
"Warm static compression" isn't a thing, if you are saying "warm cranking compression" and saying it actually runs, then it just isn't opening on the compression stroke, it wouldn't run or build any compression. If it doesn't run, then I'd ask you elaborate a little more
However, between old Jeeps and old Fords, not new to me, but I haven't ever done more than follow book procedures on those (and it's been a LONG time at that) not sure how anything, even a Briggs and Stratton can run if the exhaust opens on the early downstroke or near TDC
I may have books to see how to time it, especially if it is a 9N tractor engine, but haven't dusted those books off in a very long time