Like they said over there on supramania you will have to pull the head back off to actually find out what is going on. The rivot that they are talking about will not cause the oil leak. Might be a dumb question but did you put the head gasket on the right way? Anyways they might be right on the timing cover not being milled enough also.
Grimhack said it all, and he is competent. You just want to hear an easier way, but you must redo everything, and check for the rivet, and the timing cover to be flush with the block, and that there is no crack in the head also. Make sure the head isnt warped and make sure all seals are good,
The rivet is on the exhaust of the motor towards the front. Its very close to the Cam Position sensor location so I doubt thats your problem. I know more than one person who has kept the rivet and not had problems(including slow66). Regardless, theres something else leaking.
Are you sure the main rubber pcv hose that runs from the block to the valve cover(ntext to the filler cap) is attached and not leaking?
timing cover to be flush with the block, and that there is no crack in the head also. Bakce sure the head isnt warped and make sure all seals are good,