318 Oil Pan Gasket/Sealing techniques?

I too faced your same problem with my '72 318. In my case, it was time to overhaul a 50 year old engine. Wasn't really sure what the actual mileage was. For me, it really wasn't worth my time to do all of that cleaning and to renew the gaskets and seals, and not just overhaul it. I could afford it. You should probably replace your timing chain while your at it,and take a good look at your camshaft.
Good luck sir!