Combat, if you buy a new piston ass'y as I did (picked it up yesterday, it was actually an in-stock item at our Big R store!) you will NOT need the Frank Bowman ring. My new two-ring piston has rings identical to the ones described from Frank. They both have a shoulder that fits over the pin in the piston's ring land. To be sure, I removed one of the rings and put it in the cylinder and couldn't get a .003 feeler in the gap. It looks really good, too. The part number again is:

MTD 753-04367 and it was $29 at Big R.

Not as cheap as online, but I didn't have to wait for it to come in the mail either.