I haven't got any speeds etc. immediately to hand from last year's Classic but I doubt that Rahal and Redman were hanging about in the 917! I would certainly expect the fastest guys in the Classic to be running quicker than, say, a GT Porsche.
(In case you suspect a degree of favourtism towards the classic cars from one who doesn't exactly fall over himself with enthusiasm for GTs, I will be happy to be proved wrong....
)