Stickbuilder:

Tail Wind is talking about the 97" Gee Bee. The 82" cowl is about 10", but I don't have mine here to measure.

OBTW, an 18 x 6 at 7500 is only 45 mph. That is awfully slow for anything other than a Telemaster. I think I'd try a 17 x 6 or a 16 x 8. Doesn't OS recommend about 9000 rpm for that engine?

Jim