What I did was to make a gasket out of one of those thick green file folders,
the very stiff ones, to fit the space between the pan and the timing cover.

This is one of those places where, if you grease the pan gasket lightly on
first assembly you are much less likely to destroy it on subsequent disassembly.

(I learned that in Panama where odd gaskets are sometimes very hard to get
on short notice.)
--
George Downs Bartlesville, Heart of the USA!