10 inch or 11 inch clutch on same flywheel?

[yonah]

Pulled the clutch out of my '67 c10 yesterday. It has a 10" pressure plate with a 9-1/8" disk. That's is a no-brainer mismatch. Anyhow my local parts guy claims that either a 10" or an 11" clutch set will work. I would prefer the 11". So I measured 11" inside my 10" cover and 11" comes almost to the holes for the bolts to the flywheel. The Store would have to order either one in, I would like to get it right the first time. Does anyone know if indeed that is true, will a 10" or 11" work on the same flywheel?