"....What do you think of using a 55 gallon drum kit from Northern tool for a heating stove?"
I don't know anything about it. Does it stand upright or lay horizontal? I think horizontal would be better.
My main concern would be the lack of thickness of the steel....
The only "thin metal stoves" I've heard folks talk about is the lite sheepherder stoves --- and some negative comments there.
#1 - Get what you are going to use and try it out with your tent in the back yard now while it is still cold outside.Personally I would go heavy duty. Ask RedRivrHunter, they use a lot of homemade stuff.
#2 - I recommend taking a second source of heat. I like the Mr. Heater Double Heater (no buddy anything) as a back up. If number one fails, then you have back up. If it gets really cold, then you have reinforcements. If you need to warm up the tent fast in the morning it will do it. Simple and quick. You CANNOT sleep with this on, but then there is all the rest of the time, besides, as much as wall tents breathe I doubt they would be a problem, we take both smoke and CO detectors just in case for overall protection