You have to check out Cimarron's "old Model" frames...no crossbolts. The base pin is retained by a screw in the frame.
Cimarron carries them by both Uberti, in their Model P line (Model P Old Frame) and by Pietta
http://cimarron-firearms.com/Pietta/...FrontierOM.htm
Pietta makes the GW II for E.M.F.