I could move this over to Vintage, but let's just leave it be for now. I think Paul's advice is generally good. Do what he says and you have no doubt the carb is not choking the compression test. Since the /2 carbs are slides, you can take the air intake tubes completely off (definitely do that) and then roll the throttle completely open. Then with your second and third hand, do the compressions test. It's just a few nuts and the carb comes right off anyway. If you do it the right way, you remove any doubt.
Thanks, good direction to start. I almost posted there (vintage) but wasn't sure about response time.