I am pretty sure the birdshead Ruger is ok in SASS.
The "Vaquerito" .32s are pretty popular these days.
I think common calibers are convenient but not essential. I have got the .44 Special cylinder in my SAA .44 Spl/.44 WCF combo now because I have so many 240 gr SWCs on hand that it pays to shoot it that way as much as possible and manage Specials for it and .44 WCF for the other SA and Winchester. Surely you can tell the difference between a .45 and a .32 on the rare occasion an on-the-clock reload is called for. Gonna be hard to find a .45 - .32 combination cartridge belt, though.
You really need to get on the SASS Wire and see what is going on.
http://www.sassnet.com/cgi-bin/ubbcgi/ultimatebb.cgi
Uncle Jim
SASS # 3879