Wouldn't know, I've never seen a "live" Pentac lens, only photos. The back of the AE lens with the threads has an OD of about 77.5mm, if that's any help.
Originally Posted by adelorenzo
However, I think we can make a lens board for the Pentac lens, but we'll need precise measurements and photos, plus the actual thread specifications...
BTW, Jo Lommen, who makes really nice boards for the AE and Pentac, says that the Speed Graphic/Aero Ektar board can also be used with Pentac, with a "few inches of teflon tape": see THIS LINK
I guess that means that the Pentac threads are a bit smaller (therefore the Teflon tape). I can't vouch for the results, though - haven't tried it myself (don't have a Pentac lens, like I said).