The permanent fix is to machine the back of the block and the rear main bearing cap for a full circle lip seal like the late model Chevy V8's run, but that requires a complete teardown of the engine to a bare block, and a machinist willing to do the job. The seal is 3 7/8" inside diameter, 4 3/4" outside diameter, and 3/8" thick. I have a home-brewed fixture for my cylinder boring tool to do that job- - - -otherwise it takes a Bridgeport milling machine with a right-angle cutter adapter and about half a day of setup work.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!