O-rings are designed to seal with no gasket goop. Gasket goop could even interfere with proper seal of the o-ring. O-rings are made of pliable, high temperature synthetic rubber compound. In higher pressure applications the o-ring acually distorts under the pressure to seal even better. If you choose to replace the outer o-ring again, use motor oil to insure that it slides easliy into the ring in the distributor base. Make sure there are no twists in the o-ring. Lubricate the o-ring with engine oil, or vaseline, when you install the distributor. If the gasket goop you used on the o-ring keeps it from moving, you could be contributing to the problem. I was a jet hydraulic mechanic in the service, and I have replace hundreds of o-rings. The only time they leak is when they are worn and hard, have a twist in them, or are cut at installation. I have had trouble on one of our cars with the valve cover not making contact with the gasket where it passes over the cam bearing hump at the distributor end. A little careful flat filing to remove material at that end of the valve cover took care of it.