Hi There,
Im pretty sure I used the Mk2 Mondeo servo too and just looked through parts books until I found a suitable master cylinder with standard RST Piston size. The common replacement was the non RS master cylinder which had a smaller piston and gave a slightly spongy pedal.
I welded on a couple of brackets to widen the standard Mondeo mount, wan't hard. However the brakes bound slightly when hot, having thought about it a little I think the master cylinder wasn't fully closing which means I need to adjust the servo rod length a little. I also seem to remember spinning the servo round by 180deg so the vac hole was in the same place as the originoal (or atleast close).
I'm sure I have some pics somewhere!
Good upgrade either way.
Rob,