<< There is an oil filter element that I don't know how to find, and a duct that runs from the oil filter to the carburetor. At one end the duct is about 2 1/8 inches in diameter, and the other about 2 1/4, and should either contain a 90 degree angle, or be appropriately curved. None of the ordinary stores >>
Irv - That is the AIR filter that you are describing. The oil filter is farther back and closer to the engine. The top covers do look similar, both having AC cast in them, but serve a completely different purpose.
I don't have my parts book handy or the STAR Spares catalog, but I'll check them tomorrow to see what is available.
"Ole" Olson