My car has 400# F, 300# R springs with MM Bilstein Sports. The car also has Delrin bushings with forward offset control arms, 96 spindles and 275/40/17s on 03 Cobras all around. You will need to do some flaring, rolling, cussing with the front fenders, but it'll work. Or you can be like me, purchase some Tiger Racing fiber glass fenders......and then store them in your parent's garage!
The front tires are close, but don't rub the front springs.
I purchased the Sports (and springs) at MM's recommendation. I probably should have just bought the Bilsteins and driven them with the springs at the time (350F, 250R), but I didn't! The 400/300 springs are actually quite streetable. I now DD the Mustang since my previous DD was rear ended and totalled.
I'm not trying to start another Koni/Bilstein war, but have you considered Konis? I went with Bilsteins because I already had the Bilstein coilover kit. If I had the money, I would have bought Konis, Koni coilover kit and the new springs. If you decide that Bilsteins are for you (I truly do like them, just wanted to try Konis if the money was there), I would say springs for the MM Race2. That way you still have room to go to stiffer springs.
1993 GT 310rwhp / 351rwtq
AFR FTI EDEL Combo. MM, T-56 3.73, Brembo, 275s on 03 Cobras all around