The quick way to check for a compression leak, either a head gasket or a cracked head, is to fill the engine with coolant up to the level of the thermostat housing with the thermostat out and the upper hose removed. Take the fan belt off to disable the water pump, fire up the engine, and goose the throttle a few times. The engine will run for at least 30 seconds without boiling the coolant near the cylinder walls. If you see bubbles, or get a gusher when you accelerate, there's a compression leak.
Jerry
