There will always be some blo-by present even in a fresh engine, its a pretty rough way to check engine condition. like DD said, check your valves for seal using liquid, check the top of your block and the bottom of your head for straightness, if they're fine and the top of the piston also looks fine, put it back together with a new gasket, then comp test it again, if it's still off, get a leakdown test done to check the condition of the rings or put a couple drops of oil into each pot. If the oil raises the comp its usually rings/piston, if it doesn't, it's usually valves.

Cheers Dave.