Could just be sticky valves. I've been having more trouble with that problem as the quality of gas seems to head down.

You could take the valve cover off and check the valve lash, and tap the valves with a hammer to make sure they are moving properly. They don't have to stay open much to make you lose compression. 

Also, double check the point gap. I was helping with a 64 Olds about a month ago that had a couple of worn lobes on the distributor shaft, and the point gap was a little on the narrow side. We opened the gap up a little, and that was enough to get the 2 dead cylinders firing again.