quote Chacha53:
. The gasket looks factory, not homemade. Maybe for a different model?
I’m thinking that the gasket from your motor is actually homemade, and the maker forgot the cooling ports. I have a N.O.S. Gasket PN 43-221 and took a picture of it for comparison. Notice on the picture of your gasket, some of the finer details of the mating surfaces have been simplified.
Improvise-Adapt-Overcome