Shovels and pans were really good at marking their territory. Even with running straight 50 weight oil. I can just imagine what it would be like with synthetic oil in one. Once you heated it up, that super thin, slick synthetic would probably run outta that old girl like grease thru a goose.
Now, if you would do a complete rebuild, and using the latest sealants, gaskets etc, And new parts in the engine, It would more than likely work just fine.