I have a front photo of James Dean, washing his Speedster. I measured the front PORSHCE script emblem. It's the same distance as the head light rim diameter; which checks out to be very close to 8.5" Thanks for your help.
I met a Speedster owner, here in Tucson. He had actually glued on all his emblems. I feel for the person that has to paint the car in the future.
Paul