Twoisn't likely to end well for you. I would do 3 or one. 3 still might not work out, but your odds are better. On the other hand, 55 isn't very big so if you did 3 centropyge angels you'd pretty much have that tank stocked. I've kept trios of potters angels in the past relatively easily. I tried a trio of flame on two different occasions and it was a lot harder. Attempt one seemed to work well until one died, the remaining two were going to kill each other. The second attempt failed hard one singled another out from the start and I had to separate all three. I did this in quarantine, because it's easier.
Another problem is that some fish that get along in a cramped qt will fight harder in a larger DT -- easier to defend a patch of rock and single a fish out. I've mixed coral beauty and flame before without too much trouble but always with a third fish, one was a fireball and it did fine.
You never know with centropyge but the only real chance you have is adding them at the same time...
