Poor Man's Leak Down...Will This Work?

Quick question for you experienced guys! I want to do a poor man's leak down test. Please tell me if you think this will work or am I wasting my time. I only have a compression tester, but I do have a small compressor. I want to take the compressor and run some air through the compression testers fitting into the cylinder and listen for where the air is going. However, since cylinder 3 and 4 are the ones that failed the compression test couldn't I stuff the air in one cylinder, place my finger over the other and see if it builds up pressure? At that point it would seem most likely a bad head gasket right?

Okay, that's fine, all I want to do is narrow it down before I start to tear down. If it blows over and it's just a head gasket then I'll start the tear down. If it blow and I hear hissing coming from the oil fill and/or dipstick then it's going to stay as is becuase I donlt have the money to pull the moto and have the thing checked out further, not to mention the repair charges of blown rings or damaged pistons.