Summer tires today make a large difference in traction versus all seasons, which are still way better than any 1970 tire. Put summer tires on that GTO and I bet the 0-60 time would come down 0.5 seconds. Or more. Sports sedans today can generate 1.0 g on the skidpad, way more than a sports car from 1970.
Tires are amazing really when you consider they appeared to be largely optimized by 1980 or so with little additional benefit to be had.
If you can manage it, running summer and winter tires in season provides a large benefit.