No issues on the inside, as I have 1 1/4" clearance from the tire to the spring with the 245-60 x 15 wheels. I assume you are using the inboard rear end snubbers and have removed the factory Mustang snubber sheet metal.
I do not like running the track tires on the street as they pick up too much debris and sandblast the body here in Florida. I like the Comp TA's just fine on the street, as sudden downpours are common and I'm glad I have some tread. I've put over 16,000 miles on my replica and try to drive it as much as possible this time of year since the temperatures have moderated. It is no fun in 95-degree Florida summer weather unless you enjoy a moving sauna. My first long trip to Charlotte from Daytona, my right tennis shoe started to melt on the floor pan, so they do get very hot from the exhaust system under your feet.
Good luck and have fun.
Don
gt350bp