NitroX,

There is a website, British Militaria, and, on this site, is a Martini-Henry Forum. Lots of info of the sort you are seeking. I found it while looking, same as you, for info on a .32-20 Martini I found up here in Alaska. I'm still debating whether or not to pick it up. These things, according to the forum members, have been converted into quite a few different and interesting calibers as well as the original .310 Cadet. If you have a problem finding the site, let me know and I may still have the info around here somewhere.

Joe