I'm gonna have to stand by what i know about GT40P engines...with a few basic addons they can be 12 second engines. You however have regular GT40s, but really you should still be knocking on the 12 second door if the rest of the car is up to par.
Seriously though....it's a bit of an extreme but a basic bolt-on 302 with GT40P heads can run very high 11s with a dedicated quarter mile car wrapped around it.