I have a Mustang II front end and Ford 9" rear end. Here's what I used:
- Front: Wilwood Dynalite 4 piston. Mine are black calipers and red are available as well. Current lowest cost offering uses grey anodized calipers: https://www.wilwood.com/BrakeKits/Br...emno=140-14271
- Rear: MBM DBK9- Universal Ford 9" Rear-End Universal Disc Brake Kit. These use GM single piston calipers with integral parking brakes, simplifying the setup as well as being relatively low cost. MBM doesn't offer this for 8.8" rear axles, but I believe the Right Stuff ZDCRD03 kit is comparable and will work for 8.8" axle housings. https://www.getdiscbrakes.com/zdcrd03
- Adjustable proportioning valve. Many available.
All of these are widely available online and through local speed shops.
I don't know about 'correct', but I know the Wilwood front brakes get lots of appreciation from those attending show and shines. GM calipers are kind of 'meh' - but they do the job, especially when the fronts do most of the heavy lifting. I don't think they'll negatively impact resale, but if that's a concern you could go Wilwood in back as well - albeit at a much higher price point.
Hint: Get speed bleeders / quick bleeders while you're buying brakes and put them in with the installation. One pair for each front brake (upper pair of bleed screws) and one pair for the rear axle. They're worth their weight in gold as far as I'm concerned.