I like to always use a Sargent plug follower it has the notch on one end for mortise cylds and the other end has a large hole drilled in it deep to accept the offset Sargent cylds plus can allow for many locks that have the tailpiece attached as mentioned yet some tailpieces will be too long then you should have the 4 piece set of hollow HPC follower set just for those.
You can recognize this type follower because it has the slot cut about and 1" length ways on the end with the hole to allow for Sargent key in knob cylds with drift pin sticking out the side a must have if you want to rekey older Sargent knob locks although the keedex master follower has that too. I have one of those but never use it great gimmick but can cause more hassle than it's worth.
Improperly used short top pins will fall out and you think you dropped just master pins and put it back together to only find your customer is locked out with the spring wrapped around jamming the cyld. And then there is the spool pin problem once turned now you have to drop all pins and reload them. The black Sargent follow is the one of choice for me on just about any occasion and it lasts forever been using the same one for 30+ years now.
Richard