I have a 305/30/19 front on my mustang on an 11”.
The gt350 has 295/35/19 stock (10.5”) but I don’t know if either will help you.
I agree, 12” up front will be a major stretch.
"The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents... some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the light into the peace and safety of a new Dark Age."
-H.P. Lovecraft