CYA from 60 to 90 is often recommended for a SWG. With CYA at 120 you will need to keep your FC level higher, maybe 5 or 6, it is workable but not ideal. I would plan on lowering your CYA towards 80 or 90, but you don't need to be in a rush to do it right away if you haven't been having any problems. The crucial thing is that you don't do things which will continue to raise your CYA level, like using dichlor or trichlor.