Just my opinion here with *some* vette experience.
The straight lines that you see throughout the paint are the hardest to remove, the "swirls" will easily be removed.
The paint is *really* hard and will IMO require the use of the rotary. I know you will start with the least aggressive pad/product combo, but be prepared to step it up a notch.
If he wants it perfect, prepare to use a wool pad and several polishing steps. I would explain to him about the thinning of the clear and see if he thinks the juice is worth the squeeze.
Good luck!!