We have a hundred year old home with existing coal-burning fireplaces and we want to convert the living room one into a ventless gas burning type. Gas logs are too long for the existing opening. I ran across an insert in a catalog, but lost it over the holidays, and don't even remember what it looks like (hey, a senior moment, ok? and I have small kids). Have you ever seen one like this (fits the smaller openings, not the typical heatilator types)? Do you recommend any other way of retrofitting this fireplace without building the whole thing out 15", which is not an option? Any small gas stoves out there I can use? Thanks for your input.