You could use the single piston tbird brake calipers but as others have pointed out, using the dual piston calipers from a 99-04 mustang GT is a significant upgrade. The reman parts are cheap and enables something like 50% more pad. It's the first brake upgrade most people do on the tbird even with the stock rotors and stock caliper bracket. Search for pbr brake upgrade. There are some nuances that you need to be aware of but you can find them out by reading the threads.Thank you for that information. My main concern was being able to rotate tires from front to rear and not running into any issues with the wheels not fitting both of the hubs (front & rear). I was actually planning on using the Mustang rotors and actually found yesterday on Rock Auto the dimensions for the front rotors for both the Mustang and Thunderbird are the same as far as overall diameter as well as the hub center diameter. The only difference being the bolt pattern between the two. As far as the front calipers, since the rotors are basically the same size, wouldn't the stock Thunderbird calipers still be able to be used? Again, thanks for any info.
The only reason you'd run into issues is if your stock setup were sport brakes. In that scenario, your rotors would be a different size (11.5" to 10.9" or something like that) so the caliper brackets would be wrong if you go to a mustang rotor.