Hi all (my first post on "Project Puma"). I might be a bit late responding to this but it can't do any harm.
I've just acquired a set of Mk2 Mondeo ST24 calipers, carriers, discs etc. via eBay and am fitting them to my Puma. I've learnt by experience, from the forum and by lurking around the similar Fiesta forums that I need to:
1) drill out the holes in the upright (I used a 12.5mm drill - I hope that isn't too big. I've since seen other instructions that say use 12mm) to fit the larger Mondeo caliper bolts
2) Shorten those caliper bolts by about 3mm (or put a study M12 washer on each bolt)
3) Fit a 3mm spacer between the hub and the disc. These used to be available from specialists like Pumaspeed and Pumabuild but, seemingly, not any more. (Several contributions on various fora say the spacer is requitred to centralise the disc in the caliper. It is but I'd suggest it is also to move the disc away from the bottom ball joint - on my car it was very close indeed.)
4) Depending on the wheels you are using, you might feel it worthwhile to put longer wheel studs in the hub.
5) Shave the caliper - I don't think that's necessary if it's a 280mm disc set-up (but I haven't yet got as far as that so might be wrong).
If anyone has got an unwanted set of the 3mm spacers please let me know - I'll buy them (it'll save me making some).