I can hit 500 (508 actually) skill, though trying to find someone to lend me Hyksos Hat to test is proving rather difficult.

Whilst cure-power seems uncapped (or, specifically, that the cap hasn't been reached yet), what he was looking for is verification that any surplus (500+) healing skill isn't reduced to 500 for calculating the base cure power.

Presumably, it should be easy enough to test, if sufficient gear is available.