I'll just use the thickest gasket material I have and I should be fine
I've been making gaskets for the sump plate on a few of the 650's I've had and as long as I make sure that the surfaces are good and clean I haven't had an issue
In fact everyone I have opened up I'm sure the gaskets were the original ones (stuck tight)
Hell back in the mid 70's I didn't even know enough to remove the sump plate and check the screen I just changed the oil and kept putting miles on it