Hi i live in a victorian house and have a fireplace with the original surround but unfortunately the insert has been removed,and bricked up to leave a small fireback.I intend to replace this with an original victorian insert but just for decorative purposes as it is in a bedroom.I was planning simply to enlarge the hole and to fix the insert just behind the mantelpiece and perhaps use no more nails to secure it further.Would this be ok.?Any suggestions would be great.