Danny,
I've done quite a few ...mostly that had to look good from both sides.
I may mention some obvious things that you are already aware of, but better said than not.
Leaded and stain glass is quite fragile and needs a substantial frame to give it support. The glass easily sags and when you work on it be sure to support it from below so it doesn't sustain damage from any force including the force gravity will exert from the heavy glass and leading itself. If it is in a particularly fragile state you may want to consider either restoration or glazing over the surface.
Do not clean anything off the window except for dust and stuff that a good glass cleaner takes off. I usually discuss this quite thoroughly with the client before even removing any paint splatters on flat surfaces of the glass itself.
Old stain glass windows develope quite a character of dirt and grime and paint splatters and who knows what which is quite often considered "character" and highly desireable. The patina the lead acquires over a long life shouldn't be disturbed. Cleaning or, God forbid, buffing the lead is akin to painting antique natural wood furniture in most collector's eyes. If a client wants cleaning beyond taking off the cobwebs and paint on the glass itself I always try to talk them out of it and usually successfully.
I don't know if the antique aspect applies to your piece but quite likley does.
As far as making it look good from both sides:
If hanging in a window the front of the frame usually should face out into the room. I finish the back of the frame in any number of ways with stains, etc. usually to blend with the front and put a simple quarter round moulding available from Lowes,, Home Depot, or your local modeling hobby shop stained or finished to match. Sometimes I'll get more creative and choose a moulding that has a rope design or some other motif that fits the clients decor and setting. The flat back of a frame moulding lends itself well to either another decorative moulding strip on the surface or other types of ornamental surface mounted decoration. When using a quarter round moulding to finish the back of the frame package I don't know of any reason to use points and never have. The moulding can be drilled and counter sink brads to hold it tight to the frame and then putty or whaterver it takes to make it look good.
One problem I have often encountered is that most frame mouldings are not meant to be seen from both sides so don't forget to factor in hand sanding and finishing to your quote to remove any unsightly stains. And nicks in the back are a problem here to where on other frames they just get covered with a dustcover and it doesn't make any difference.
If you are working with a curved surface you can steam the moulding and then nail into place and let it conform to the existing frame.
Be aware that any frame that hangs in a window is going to be quite suseptible to UV damage epecially if south facing. I know of no damage to the stain glass or leading UV could cause, but moulding finishes and stains should have some type of UV protection or overcoating to minimize damage and extend the life of the finish. For good UV protection varnishes go talk to the oldest salt at your local marine supply store.
I usually try to find some antique brass fittings for the top to attached some sort of old looking brass chain for hanging. Again be sure if you are supplying the hanging hardware that it is substantial enough and anchored in such a way it won't give way. Brass decorative surface mounted decorations look great too. I prefer them unpolished.
Can't think of anything else and my stomach is saying "feed me" so I better heed it's demands!
Have fun!
Dave Makielski
