Carpentry and Woodworking - preformed arch?

We have this interior doorway (standard wood framed) with sliding pocket French doors. It's about four feet wide. The contractor didn't make a stub wall, and it looks strange. The other two entryways into the dining room are standard plaster arches (no doors.) I was thinking of removing the French doors altogether and installing another arch.

We don't want to tear up the walls any more than we have to as they are wallpapered and the wallpaper is a discontinued pattern. Can you buy preformed arches? Either wood or polyethylene/hard plastic of some sort. My thought is to put the arch against the present wood frame and fill in any gaps with "gingerboard" cutouts or lattice work.
Any thoughts appreciated.
Thanks!

Sorry about the late response, but I was trying to locate the manufacturer of preformed trim I used a long time ago, but to no avail. But they are out there, and can match any molding you already have. It may cost you a setup charge, and it may be cost prohibitive, but sometimes you can buy molding already preformed. Take a measurement from the inside to inside of where you want your molding to land at the door, and then a measurement from the center of the door opening to the height desired. Go to lumber salvage yards and see if you can find a matching arch. Quite often they have such items that were ordered and never used on new homes.

I've never used them, or endorse them, but here's a place I ran across online...


http://www.creativecorners.net/