I maintain that you're better off holding out for a PP1 car, if tracking it is your intention.
I spent some time reading the thread posted above, and it appears a PP1 brake swap is not as simple as it first appears, requiring the PP1 master and booster as well as the front calipers and rotors. In the thread, they never posted the cost of those parts, but I bet it wasn't cheap.
As I mentioned above, the PP1 isn't just wheels, tires and suspension. You get a bigger radiator, torsen diff, different programming in the vehicle stability and abs, etc. There's been a fair bit of discussion on the Mustang forums about this, and it's pretty expensive to bolt on all the PP1 parts after the fact, and you still won't have the stability programming.
There are deals out there on PP cars as well, just takes some looking.
My formula (budget version) for HPDE would be a discounted (or low mile used) PP1, then add:
19x11 wheels w/ 305/30-19 NT01s - $2500-3000
Ford Performance "track" shocks - $600
BMR SP083 springs - $250
Camber plates - ~$250-300
IRS cradle braces - $250
Brake pads of your choice and fluid upgrades
Rear diff cooler - ??? If needed, this looks to be pretty expensive, but the aftermarket hasn't really got moving on it yet.
The above is pretty much exactly what I plan to do. Ours isn't going to be tracked more than a couple times a year, since our Miata is the primary track car, so I want to keep it streetable - thus no roll bar/seat/harnesses. The above list is ~ $5k, and we were OTD for under $30k on our '17 PP1 (bought used w/4k miles). Still well under sticker on a new PP1/2.
My biggest problem is we recently drove an '18 PP1 with the new A10 transmission... both the wife and I really liked it (and we both prefer manuals...). We're considering trading up to a '19 next year if we can find a a really good deal on a PP1 with the A10, magnaride and active exhaust. It's a good thing Grabber Blue isn't an available color for '19...