Freedom Arms makes a pretty snazzy single action, but it's not cheap.
USFA makes or made a single action also.
Bond Arms has a 3-inch double derringer.
Ruger has the 5.5" 8-shot Blackhawk and the 6-inch 7-shot .327 GP-100.
Hammer It has a Hamilton Bowen converted S&W Model 16-4 that
all of us .327 guys just
love.