No 12 " clutch is an upgrade. I took out a perfectly good Sachs clutch and had a 12" SBC Con-O put in because I was afraid I'd slip the Sachs. Less than 2 years later the center of the Con-O broke. Never slipped, I was under the 400 HP/ 900 ft. lb. rating.
$1400 later, I have a 13" clutch again.