Front backspace 17*8 on dart, final advice before buying

I have a 67 dart, i upgraded the fronts to the 13" mustang brakes that doctor.diff sells as well as the mustang rear brake kit. I decided to run the american muscle mustang rims in 17x8 (5.72" backspace, i think). Im running 235/45/17 all around no need for spacers on the front or tie rod issues. For the rears im running a small custom 3/8" spacer to give me a little clearance and to match the hub difference between the lbp axles and the wheel hub. Im pretty sure i could fit 245/45/17 all around with this setup but i wanted to be conservative at first. The 235 tires are bridgestone potenza s04 pole position and according to tire rack measure out to 9.3 section width and 8.5 tread width.