how much power can it handle?

If you're running nitrous or boost, you've got to be careful, as these can heat up the top ring (causing it to butt and seize, breaking the top ring land) or detonate excessively hard, potentially fracturing the piston.

You need the proper tune and that the top ring land is so close to the crown you'll have to run a really wide gap on #1 compression ring, or the ends will butt together, and the result is this: