There was a article a few years ago where they pinned a Porsche cup 911 factory racer, and Viper competition coupe, and a few other manufacture based race cars against each other. The Viper held its ground and then some against anything they threw at it. I’m sure back then that might have planted the seed to do the ACR we have now.
I’m sure the GTR or ZR1 would do unholy things also with a real wing and actual tires (cup sports would work). But the truth is unless either one of them man up and do such a thing I don’t see the Viper’s time falling anytime soon. I hope GM isn’t done playing with the ZR1, I heard the motor in it can go a little further so that would be a start. Toss a wing & tires on and go after the Viper. 
Speaking of the Ring. Did anyone read on autoblog about Lexus basically pulling the plug on their LF-A supercar? Rumor was they were having trouble trying to get their car to keep pace with the times the GTR & ZR1 were throwing out. So they are just going to use the car for development purposes rather than production.