Have you tried removing a drum from one of the original hubs and trying the new drum on it? It would be possible to machine the new hub with a square shoulder on the inside to make things work, but it shouldn't be necessary to modify an expensive new part that's supposed to be a bolt-on situation.
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!