Bud, I use one of those wood boring spade bits with the little tangs sticking out on the outside periphery to cut a nice round circle through the stainless. To get it started I punch a little hole in it with an awl. Once the hole is about half way through the firewall, I go to the other side and start back using the same hole center. That keeps from splintering the wood on the backside of the cut.
I know Sterba would drill and rebalance your prop for you. That's who did mine for Steve. Mark Langford, Huntsville, Alabama N56ML "at" hiwaay.net see KR2S project at http://home.hiwaay.net/~langford
