[1985 CCX]

Keep in mind the original cars were leaf-spring (buggy style) and much different than a coil over car. You will be better than original FIA car as your suspension is well engineered via ERA.

Original cars were in the 400hp range, as Bob stated they are familiar with up to 600. You will be fine...

Your rear gear ratio will dictate speed, these cars were not smooth in the wind hence the Coupe and GT40. If memory serves me well 150 ish was about the limit. More hp and higher gears can get 427 cars in the 200mph range. My old CCX was steady at 155 but higher was not possible as I maxed gear and hp at the time. I ran 250lb springs in the rear, Jag type

Good luck