I have a house that was built in 1940. The fireplace is rather large (I think) it is 32" high. My new Hampton HI300 wood burning insert is only 30" high. All the other measurements are good. I will be having this installed and I told them about the size diiference and they said no problem as they can install a sheet metal trim piece. I am not happy with this as the insert is all cast iron. So I want to know how I can go about resizing the opening by the 2 - 3 inches without using sheetmetal. Can I simply remove the top black trim and install a 2 inch taller peice so that it drops into the box opening to make up the difference? This would be great as I hate the look of the black marble on there. I want to replace all the black tiles as well anyway. Or could I installed a 2-3 inch cement block base to have the new insert sit on it and trim it off on the front edge? Any ideas? Am I thinking on the right page or way off here? Here is a picture. Thanks for the input.