Salamandrine - Yes. Atom was identical to Regina, never understood how that worked making them in France and in Italy and all interchangeable. In olden times Schwinn stocked replacement Atom cogs, any Schwinn dealer would order them for you, and you could use them on your Regina block. Still means that graveyard Varsity needs to have the FW salvaged.

Higgins617 - Of course we use pre-owned freewheels. Problem is it can be very hard to look at a freewheel and make a good appraisal of how worn it is. If it does look worn those teeth are cooked. If it looks just slightly used you have to try it. Might be good, might not be so good. Internals always come back with cleaning and lube. Unless you lost a pawl spring. For that you will have to open it up and see what can be done.