Need help please, 12" clutch on 67 or 11"???

[steveo3318]

Ok guys heres the deal. I have my motor out stroking it to a 383. I figured I would replace the clutch since I had to buy a externally balanced 400 flywheel from Ram.

So heres what happened and my question. My new clutch came in today and everywhere I have checked says its correct for my truck. Heres the question. My old clutch was an 11". I didn't realize this until today when comparing them. I feel like I have the truck bellhousing but don't know how to make sure without pulling it off the trans. Pretty sure the pilot hole is the larger 5 1/8 or so. Can anyone tell me if a 12 inch clutch will work????