You don't need a "leak down" tester just to find if compression is leaking from a valve, just make sure both valves are closed or looks closed....remove rockers just to be sure, and put air in the spark plug hole....if a valve is stuck open, you will hear the air coming out, THEN you must pull the head to see why!
I can give that a try to confirm what I just saw. I put the scope barely in the spark plug hole and managed to see the exhaust valve. To be certain, I put a lever in the valve lash gap and could see the valve moving as I levered it. Never closes completely apparently.
I'll check the price of a new head vs getting a new seat installed, before I do anything else.