[1795]

I would imagine that someone that drives by the seat of his pants and/or an experienced race car driver would notice differences. The frames of the originals were made from a lower grade steel than the current manufactures who use the original frame design. The originals had more flex to them, especially given the use of thin aluminum for the body panels. A fiberglass car is stiffer than an aluminum car.

If the engine, transmission and differential are kept at a constant, than I would suspect that the original might still be the quickest as the frame probably weighed less than a current manufactured frame and I believe that the old aluminum bodies were thinner than newer ones. Fiberglass is heavier than aluminum; although maybe the extra stiffness that it provides might work towards decreasing power loss through the frame twisting?

The SPF and ERA 427 frames are stiffer than the originals and will not twist like those would.

Reality is, the average driver would not really notice a difference in street driving situations. You would have to have it on a track and put the cars through some performance maneuvers to potentially notice differences.

My 2 cents for what it's worth.