This may or may not work for you, but it is a different approach and might be worth a try. Actually I tried this about 20 years ago on a 1956 Cadillac and while it did reduce the drip to an occasional thing it didn't eliminate it. I should add I was years later told the remaining leak was probably from a leaking head gasket. From what I understand, these leak predictably back at the rear of the valley pan and mimic a rear main seal.
I once watched a fellow fix a rear main leak in place using a stainless spring steel piece from a windshield wiper blade. It was about 1/8 inch wide and maybe 20 or 25 thousands thick. He measured it in the lower bearing recess and cut it, grinding one end tapered and then rounded that sharp edge a bit. With a small hammer, he slowly drove this between the back side of the upper rope seal and the recess in the block until the ends of the piece he had made were flush on both sides. Then he replaced the lower rope seal in the normal way, put gasket sealer on (the seal piece ends also) and tightened everything back up again.
Good luck!
Jon
