Good night

I'm new here and have difficulty writing English, so I use an online translator. I apologize.

I am possessed of an Escort RS Turbo S2 1988, and I'm changing the braking system;
Front -> Disks 283mm sierra cosworth 2wd + 4wd calipers
Rear -> 273 discs and calipers sierra 2wd

My questions are as follows: switch the master cylinder and a servo for a higher capacity?
Remove ABS? Yes, not ....

What do you advise in this case?

I thank you for your willingness to help me.

Thanks

 

retain master cylinder, remove abs

fit a bias valve for the rear brakes, or at least make sure the rear load compensators are correctly adjusted

 

Good advice from studabear about the bias valve

 

Personally I wouldn't bother with the rear disc setup ther than for cosmetic reasons

My car stops well on 2wd discs an 4x4 calipers with correctly adjusted rear shoes, I don't see the point fitting rear discs only to have to dumb them down with a bias valve