Ditto what Don said.
At least the mystery is solved.
Now you know why a fuel/air meter can be such a good idea - while you've got the engine out, why not get a bung welded into a primary exhaust tube?
I am surprised it ran at all if it was that rich - to fill the crankcase with petrol takes some doing.
Would not have done much for ring seal either - those rings could be pretty worn, what with all the fuel washing
oil off the bores.
Fingers crossed for the rebuild.