10-52 will be too thin IMO, i use 10-52's in E and drop D on a few guitars...11-54...getting warm, this may work on a 25.5" scale guitar but not for me, still too much flab in the strings...12-56 should work on anything in drop C...but for me, the best strings i found for drop C are the GHS Zakk Wylde signatrue lo tune strings which are 11-70...yeah it's a monster low E but man it sound so good and thick and has no flab to it at all. perhaps the 10-60 set of GHS zakk wylde strings would work for you, if not i'd go with the 12-56 EBs personally since i hate flabby strings. what type of guitar and what scale length is it that they are going on?
-Mike