IIRC, the guvna is Z frame, which is N frame with elongated cylinder window and K grip frame (RB) configuration.
I'm sure there's a schematic somewhere on the WWW but the N frame may work in a lot of circumstances.
There's also a wealth of info in the FAQ thread... FAQ
ETA:
Just noticed this thread was started almost 4 years ago.
Oh well, better late than never I guess.