One of those. Now put them back on and let's do a leak down to find out.
If you have a short block lying around and a beernight you could try them on that. You can also turn the head over with the chambers sitting up and the deck level and pour some solvent in the chambers and look for the valve that drains into the head. This will show a leaking seat. Take that valve out and then check it for straightness. If it's straight, the seat or valve job is the problem.