Johan,
Now that you mention it he did not race, but he did practice with us at the VSCDA Fall finale last year @ Mid-Ohio. I just looked up the practice times and neither the 917 or myself are listed. I was not listed because my transponder was off, perhaps he was granted a one time "practice" or show for a potential buyer.
Regardless, I can't believe it would be allowed to race vintage even with a fuel cell. Modern motor/trans and modern brakes.
I found a link to the car
Bring a Trailer » One-off Gulf Porsche 917K Clone in Ohio…
I have no connection to this car.