That's good thinking on the brass frame. The solid frames, with the top strap, are stronger than the Colt type open tops, but no reason to tempt fate. Especially when the loads you mention will do everything you'll likely need them to do with that pistol.
I'd start out around 20gr and see how she shoots and work up a little from there to the one she likes. Definitely stopping at 25gr though.
Could use a litle corn meal or cream of wheat filler if your not using a wad, if necessary.
Those are nice looking pistols and the long sight radius should make it a good paper puncher. :thumbsup: