67S Port Size

[JB]

I recently acquired a '67S motor that appears to be a very low miles, correct, factory built motor. This is an aluminum case, 911/02 motor. Upon measuring the head ports, I found that the intake port measures 35mm at the inlet and the exhaust port measures 33mm at the outlet. This is in direct contradiction with the specs for ports given in Bruce Andersons and Wayne's book of 36mm Intake and 35mm Exhaust. The valve sizes measure 42mm Intake and 38mm Exhaust which agree with their books.

My question is: Does anyone know for sure (measured actual head ports from a 67S) what the correct port size is? According to the spec books, there is no other head that shows the configuration found on my motor.

Thanks,

JB