There will probably never be a consensus, but I have recently had RAM Clutches build me custom LONG style clutches for flathead usage - and specially weighted steel billet flywheels. The guy that I worked with is named Pat Norcia - really nice guy (though busy!). He built a 10.5" clutch that bolts to a 10" bolt pattern (they are the same).
I was able to discuss the application, performance levels, etc. - to get a clutch exactly as I wanted it (along with custom flywheels).
With that said, it will not be as inexpensive as what Ft. Wayne (it seems!) used to do, but I also don't want to run offshore crap where I have nobody to work with me on what I need, nobody to discuss issues with, etc.
You might give them a call . . . no guarantees for your application . . .
B&S