Rear coil overs springs

Escorts have struts that already have coil springs on them. We used to call them "killer cars" for the number of fatal crashes caused by separating outer tie rod ends that checked fine a week earlier. I wouldn't recommend modifying anything on the steering or suspension because then you open yourself up to be a party to any future lawsuit. Lawyers and insurance investigators love to find things like that, especially when the crash was caused by the other guy. Those modifications easily shift part of the blame to you because you were less able to avoid the crash.

Do you mean the springs are separate from the shocks or struts now and you want to convert to an assembly? For what purpose? If your goal is to modify ride height, the only conversation I'll have as a suspension and alignment specialist is about restoring it to the manufacturer's specified ride height. That is critical to tire wear, which Ford already has a problem with and no interest in correcting, and proper handling.

If ride height is below specs now and you want to get it back to where it should be, the best remedy is to replace the original springs. There are aftermarket "variable rate" springs that can carry a heavier load AND provide a smoother ride. Moog used to call them "Cargo Coils", and they were sold by many other retailers and parts stores. They were real effective and popular.