If you don't get back to the dyno you will always question this in the back of your mind. Construct a game plan and stick to it.
Bring your compression tester, race fuel, headers with a 3" collector, different carb. Your engine isn't that far off and the curve has normal traits but what I don't like is that engine can't "clear its throat" until 4400-4500 for some reason. Cam and headers is where I'd look. Open the lash and see what happens. Record cranking compression before and after adjusting lash. Good luck and thanks for sharing BTW. J.Rob