I wouldn't bother with the stock ring, unless you're just curious to find out what the a difference the Bowman ring makes. For a fair comparison, however, you'll have to allow both rings to seat properly, which could take gallons. If you've already got a plane, then sure, fly with the stock ring first. Then after a dozon flights, swap in the Bowman ring. Running it all on the bench will be painful.

Running a rich mixture doesn't do a gasser much good. It just cokes up the engine faster. Better go with either 25:1 or 32:1 instead if you want to give it more oil during break in.