The rear shocker mount is not designed to take the weight of the vehicle as the mk 3/4 escort did not have McPherson type suspension at the rear. If you look under the rear end of your car you will see the spring is between the suspension arm and and chassis and not round the shock absorber. Therefore it is where the upper spring seat is that takes the load/weight of a standard vehicle.

By fitting coilovers you are putting the weight of the vehicle on the upper shocker mount which will require strengthning.