Trace the outlets from the MC back to the seperate corners and indentify which system is the causing the problem. Starting at the MC work along the system cracking off each union in turn along the way and carry out the bleeding process at each point.

I find sometimes you need to use a bit of agression to get rid of an airlock, open up the bleed nipple on the caliper fully, make sure the MC is full to brim with fluid, then pump the pedal hard repeatedly. You might want to put a cloth over the bleed nipple otherwise it will squrit fluid everywhere.

Regarding the MC that has been replaced, is it running a 1.6 size brake MC & servo or a smaller engine one? From memory all 1.6 engined Escorts run the same MC & servo as the Xr3i & RS Turbo.