Steve - attached is the ball bearing Safir specs on my GT40 clutch using the ZF. The o.d. is 1 & 3/8" to fit the SBF crank. I believe the 351C is the same? I.D. is the 17mm / 0.669 for the ZF. I will let you now in a year how it works ! This setup is being used extensively for the Ford to ZF combo.
Perhaps it could be used for the Pantera as well