Yes Mark 90 oct for the 70's american market
Mark, If you've followed the excellent web contacts provided by 937 Carrera you will notice that for fuel at the pump in the states, 90 octane (PON) is equivalent to our 95 (RON).
Just to throw a real curve ball, my '72 2.4 was originally sold in France so my handbook is in French......this states use 91 ROZ whatever that means (I can't think of any French word that fits the bill yet) !!
I get on fine with standard 95 unleaded ....no hint of pinking at any loading ....engine was set up by JZ on a rolling road. [