Installed the new flush valve today. Went in as expected, no issues. The flushing system sounds better (no more "broken clunk" feel). I'll be able to put it to the test after my 2 cups of coffee tomorrow morning.
BTW, that tank seats just right on the toilet. It's not fully seated until the front and rear ribs touch. Don't use a screwdriver on the screw in the tank, use a 1/2" long socket from underneath.
**EDIT** - put the Champ through the real world paces this morning. It's still "The Champ" and does what's intended.