As excited as I know you are at getting a new fish,I'd advise you to wait on the urge of buying another Fancy,until you do find new homes for your Commons and Shub,as that's not always an easy task to do.
If your tank is 55 gallons,you can keep two of those fish,maybe even squeeze a third one in if you do regular water changes and maintainance on the tank,and you have sufficient filtration. If you've decided that you prefer Fancies over Commons,etc.,well that's another story.I truthfully would not keep Moors with Commons as they are at a disadvantage with their eyesight to begin with.
Believe me,I'm not trying to give you a hard time here,or lessen your enthusiasm,,but we try to not only teach good care for goldfish,but also responsibility on our part as good pet owners. If you want the Fancy Goldfish then
Your best bet is to find the fish that you allready own,nice homes,before you even consider a new fish.You may want to spend a bit of time doing a little research on your choices of fancy's and the requirements needed during this time also,just to make sure that this fish will be one that you'll be happy with in the long run.
Good luck,I hope that you work it all out.