I'm curious to find out for sure. You can put on the 6 piston upgraded calipers, rotors, and pads, and it will work. Kinda. I'd still fade halfway through a session, but ACS is probably the most abusive braking track I know of.
As for what's the same ... eh? --
https://trackmustangsonline.com/threads/the-albuquerque-stripper.16040/page-12#post-256566
From my parts cataloging, with MC's --
FR3Z-2140-A performance pack manual 3 nip
FR3Z-2140-B performance pack auto 2 nip
FR3Z-2140-C base GT and Shelby GT350
FR3Z-2140-D auto 2 nipple
for BB's, they also have 4 -- and leaving my feelings out of this, these words come directly from Ford themselves. I'd hate to slander their good name.
JR3Z-2005-B Mustang. 5.0, all.
JR3Z-2005-C Mustang. 2.3L, performance brakes. Brembo Package. Exc. High Performance Brakes. Performance Package.
JR3Z-2005-D Mustang. Brembo Package. High Performance Brakes. 2.3l. High series police pkg. Without performance.
JR3Z-2005-Z Mustang. 2.3L, high series brakes. Brembo Package. High Performance Brakes. High series police pkg. With performance.
I had started with the B, and swapped in the Z. Objectively, the brake booster shouldn't matter, but as I could finally stop, and very, very hard, at least for my scenario/setup, it worked. Perhaps I had inherited a busted one with my salvage, but the typical problems with vacuum and car idling/stalling issues on clutching suggest otherwise. I have the old one if somebody wants to bust it open
My reason for wanting to upgrade is just to further complete the retrofit. The base GT comes with some 245/45/19 combo, and the PP2 comes with 305/30/19 Cup 2's. I know I run much better tire than the Cup2 now, but they also have different as built codes, which would tend to have me believe that they have a slightly different programming on it with more tolerance for stopping and G's, as they assume somebody is much more likely to track their PP2 than a base GT. The other thing of note is that the caliper pistons on the PP calipers are 36/36/36, compared to the GT350's 36/34/32. That might not seem like a big difference, but it's enough that Ford added two SKU specifically for performance packs, and strangely enough, don't give it to the GT350, who continues to share it with the base GT.
I think we could all agree that the FP350s would and should be differently calibrated, but now knowing the differences in the MC's, I'm also now more confused with how it'd interact with the MC being changed slightly, and I'm going to assume the FP350s brakes are also the 36/34/32 pistons as well.
As usual, I'm more confused AFTER writing a post, but I'm also down to give anything a shot, it's just flashing a code. If somebody can give me a FP350s VIN or As Built coding for the ABS module, I'll be willing to give it a shot.