as i said, i have cossie 4 pots on 330mm discs and the pad area fits well. they work very well, and the piston size stays matched to the master cylinder size. you wouldn't believe what a difference a rebuild can make. usually just removing the pistons and tipping out the watery old shitty brake fluid is enough to prevent fade in a lot of cases.

the only reason to upgrade cossie 4 pots should be to get a lighter weight caliper (probably ally) for less unsprung weight and / or a larger pad area. i think most people 'upgrade' to AP's or Brembos just to get the name rather than any other benefit, and it's not worth the extra cost imo.

glad you seem to have it sorted though, keep us posted and show us when you've done it