It doesn't seem like enough kneading to contribute to toughness and I also doubt that the combination of those two flours equals anything close to 14%, so it's not an excessive protein issue.
How did the dough feel on the stretch? Was it especially slack? If this flour mix is in the 11-13% protein realm, then 67% might be a bit high. It can be a bit counter intuitive but I've found as you go into more extreme hydrations, the crust can get tougher.
The Guistos are unmalted, correct? I have a theory that part of the reason why Caputo tends to be a bit tough at 3 minutes is it's lack of malt/lack of protein degrading enzyme activity. For NY, even in the 3+ minute realm, I think you should be thinking about a malted flour- if Guisto's isn't malted.
Beyond the flour selection, thickness factor can go a long way in dictating perceived tenderness. I would start by decreasing the thickness factor, seeing how the texture turns out, and then, if it's still a bit too tough, then I might think about lowering the hydration.
Nice microblisters on the undercrust.