SubieTourist

Hoping to get a little help about some issues with my Legacy. '97 Legacy L with the stock EJ22. It's overheating after 20-30 minutes of driving time. Removing the radiator cap reveals that there is coolant missing from the system, and it is not pulling coolant back out of the reservoir. If coolant is put back into the radiator again, it will run without overheating until once again enough coolant is missing to cause an overheat. There does not seem to be coolant leaking onto the ground anywhere, regardless if the engine is hot or cold. The oil does not seem to have any coolant in it. After replacing the radiator, radiator cap, and thermostat, I finally took it into a shop, who within the hour told me it was a blown head gasket. I'm not sure how they were so sure, so quickly, unless they checked the coolant for gasses. In contrast to this diagnosis, everywhere I look on this forum people are saying "EJ22s don't blow head gaskets." but an internally blown head gasket seems to fit the symptoms. Is there anything else I should check? If not, what are the best options for head gaskets?