[Three Peaks]

Agreed. It would have been a holy terror on the Ferraris at the same time the Cobras were being thrown into the mix. Lighter than the Cobras, better aerodymanics, and the heavily developed Chev small block would have made it the car to beat instead of the Cobra.
Even when the coupes were developed for the aerodynamic advantage, I think the Gran Sports would have been tough to beat with a good driver.

Also, with the GM resources available, they probably could have signed any driver available at the time- and there was some considerable talent available in those years looking for rides.