As long as the car you want is in the 65 Corvette class, Philip, it's selectable.
But - I've just seen the Amir's pull out which takes us down to 6.
6 drivers is pretty thin, especially on a punishing track like this one where it's entirely possible to wipe out on lap 1 and knacker your car up badly enough to need a quit. 7 was borderline, but on a track like this, I don't think it's a big enough field, I'm afraid.
OK - I'm going to scrub this one , and have a rethink about its current form. I don't want to run a disappointing event, and waste people's evening.
Maybe we will try it in a smaller and more controllable car first.