should be perfectly fine with the kit you have, but if you want to go crossfire in the future you may find the rad starting to struggle a little
sorry didnt notice it was crossfire already you will be able to run it but you will find the temps higher it might be worth getting the kit in seperate parts for this set up, so you can either get a quad rad to help boost performance, or getting the kit and adding a dual rad to the loop.
you will also need a crossfire connector for the two waterblocks