I am retired but want to help others the best I can so considering having caliper brackets made from my 11.75" GT rotor BBK and selling just them or providing a full brake package so you do not have to buy a kit and end up with brackets you do not need left over.
The WW BBK can be ordered with the slightly smaller rotors already, that is what I did, drilling the rotor hats for 4x100 does not need to be done at a machine shop as the rotors are hub centric, not stud centric. Stock rear rotors can be drilled DIY as well, same issue, the holes just need to be a bit larger than the studs, just like the stock holes are. That means you can just get 4x100 hubs which is not that costly.
There are 15x8, 11.4lb, 4x100 roll formed wheels that will fit as well as 15x9, 10 and 11" wide, $159 each for the wheels in 15x8 and in stock.
The 15x9 I run are 13.4 lbs, roll formed, $124 each but require a rear camber change or flares.
I will test fit some 15x7 11lb wheels soon to see if fit over my BBK as well.
If you had flares you could run the 15x10 and maybe 11's with the right flares but only race tires are made wide enough in 15's.
Rough estimates:
4x100 conversion, DIY as much as you can, $200
15x8 wheels, $680
Total $880
------------
11.75" GT rotor(race grade) BBK $1200 6 piston red calipers, custom brackets, top quality rotors, pads, SS lines
4x100 conversion 200
15x8 wheels 680 (roll formed low cost 15x9,10 and 11" wheels available, 15x7 for around $480 a set)
Total $2080
I would gladly turn this over to a vendor to make instead and just stay retired, if somebody will do it!
Rick