I've got a 1973 Evinrude 9.5 HP with an 8 1/8 x 8 prop (#383315, best I can tell). I'm using it as an emergency back-up engine for a deck boat. Right now WOT RPM is 3700, so I want to go to a lower pitch, and I've seen some 8 x 6 props advertised for this engine. I'll buy one new if need be, but...