I don't know, but there is only a handful of gunsmiths in the US who do custom conversions.
I've always thought that a six shot conversion would be cool. It wouldn't be that hard eigther, cept for turning a new cylinder, though it would be timeconsuming and expensive.
check out
http://www.armsportllc.com/Don't know if he's done one or what it would cost, but it would definatly be a fun gun, and 22's are cheap!