If there's a salvage yard in your area that deals in big trucks, it's possible they would have the flywheel you need. or know where to source one. The larger diameter flywheel also allows a heavier duty clutch to be used, one that won't fit inside the standard size bell housing.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!