How about the FRPP 03 Mach 1 wheels? 17x8 with 5.72" backspacing, will they stick out too much?

 

I have a set of orginal 95 cobra R chrome 17X9 with 24mm offset and Nitto 275/50-17's on all four corners.They do stick out a tad maybe a quarter inch but changes the stance and appearence of the car.No one I've talk to thinks it looks out of place.Gives it the Mustang Reto Muscle car look.No rubbing or and noticeable problems with handling or steering.I really like the Nittro's. Here a picture

 

Yes, with that backspacing those wheels would stick out too much... just as any other pre-05 wheel would.
If you like the Mach 1 wheel, there are aftermarket versions available with the correct offset.

 

2001 Ford Racing Bullits...............NO fitment issues

 

Aftermarket Bullitts (OE Concepts)... Fitment is awesome and they're designed based on the older Bullitt style.