Check out any of the thirty-nine Crankcase components enlisted.
Some items from this specific schematic: Oil Seal,14x28x7, Oil-seal 4.8x14.5, B/brg Rad N/com, Screw,pan,6x65.
The most reasonably priced component used on the Mt125 Elsinore 1974 K0 Usa Crankcase is the Screw,pan,5x16.