Can an aluminum flywheel be used? IF I reminber right the old GCR said "made of same material."
Here is what the 07 GCR states.

"m. Any clutch disc and pressure plate of stock diameter may be used, provided that they shall be bolted directly to an unmodified stock flywheel. Balancing of the flywheel/clutch/pressure plate assembly is permitted. Lightening of the flywheel beyond the minimum material removal necessary to balance is prohibited. The addition of an external scattershield per GCR 9.3.39., is permitted and recommended."