Wow, 13 months later...

I will agree with what was said above. You are wasting your time (and our advice) by doing things that have nothing to do with a) diagnosing the problem or b) fixing the problem.

Pulling head bolts and blowing air into them means NOTHING. You have determined you have low compression in two cylinders. That is the extent of the diagnosis. A lead down is nice, but who cares. It won't change the next step of pulling the head. It does not matter if it is the head, the valves, the gasket or the block, but the next thing that must happen is for the head to come off the block.

I do wish you luck. I don't know what answer you are looking for, but this thing needs to be torn down. As stated above, the more common problems in these engines are the gasket burning between two cylinders and valves burning. After that I would say a crack in the head is next with a cracked block being last. But, you can know what the problem is without looking at it.

Michael