I've replaced my O-ring twice, first with an aftermarket, second time with a Honda O-ring. Stopped leaking for a few weeks, then started back and now leaks worse than ever. Did the first 2 myself, taking it to a shop to do the next one.

 

Are you sure it's leaking past the O-ring?

Another possibility very close, is the split line of the camshaft bearing cap. Look at the lower photo in post#8. The hole where the distributor mounts is made up of the 2 parts bolted together. The lower part is the cylinder head itself. The upper part is the last camshaft bearing cap. They're supposed to have sealant, not just bolted together.

If that's it, the oil will actually leak out that horizontal line between the upper & lower part. It comes out of the distributor base, just about the same place the oil comes out when the O-ring is leaking.