my 45+yr old king wood heater is on its last leg and metal has started to get holes in it. im thinking of buying some steel plate and building a new firebox the same size as my current heater and reuse the door assembly and the cabinet. option 2 is just build a firebox maybe slightly bigger than current one and paint it with high temp paint. below are my questions 1. what thickness of metal should i use for the firebox? any specific grade of steel better than others? 2. will paint hold up well if i go that route? 3. can door assemblies be purchased? all i have seen is the kits for barrel stoves. 4.my current heater has the pipe come out the side and elbows up and goes thru roof, i think if i build and paint the box, it would be better to come out the top with chimney, but how do you put the pipe on between the heaver and the flange in my ceiling? with the side exit pipe just have to slide it in from the side so no problem.