I'm attempting to use a 99 master cylinder without the hydro boost for my auto-x car, is this do-able? or do I need to find a vacuum booster, this is in a 93 FOX. It will use a new edge brake system.
Also what, if any rear calipers will interchange with cobra rear brakes?

 

If your talkin 97-04 cobra rotors u will have to use their calipers because the stock ones will not work, ALSO you will have to change your caliper mounting brackets at the end of each axle. And I'm sure you already have the 5 lug conversion done. I found this out because I put a 98 cobra rear end in my car and the brackets wouldnt let my stock calipers work with my stock rotors so I had to take the axles out and change the brackets.

 

the car has a 00 cobra IRS in it (without calipers) and the front spindles are 99, I'm more worried about master cylinder compatibility since the new edge used a hydro boost and that won't work on my FOX

 

I really cant help you much there, I havent really worked with changing out brake booster setups.