Tony would make easy work out of GSP. Let's not forget Hendricks outstruck GSP, and he had a difficult time taking him down. Tony might get taken down, but he is far too active on the bottom and too stringy for a thick almost immobile fighter like GSP. That is, Tony gets triangle choke on him or exhausts him enough that he dominates 3rd round onwards.
Most importantly, GSP face scratches off like a lottery coupon. He will get griugered with those Cucuy elbows and get stopped by a medical team trying to find his face.