If you can, take the guage off of the compression tester and replace it with a valve and air chuck. Then bring #8 up on compression stroke, hold the crankshaft in that position and put some air to that cylinder. It doesn't take a lot.

You can listen to the carb, exhaust, and breather to hear where the air is escaping the cylinder. Of course, hearing air from a valve cover breather means the biggest headache.

This is a simple and definitive test that will point you in the right direction.