I was thinking like Roger. Possibly 2 seals between the filter and block. An easy test, As long as there is oil anywhere on the dipstick. disable the distributor by either unplugging the center hi voltage wire or (preferred) pull the 12 volt supply. And simply crank the motor for say 8 to 10 seconds.
Then look around for evidence of the oil leaking. Since it was recently running it shouldn't take much to move oil and build pressure.

Cheap and easy = cost effective.