i dont think it is a shaker style coal stove. its a early 80s style wood stove. those angle irons you see welded in there are for fire brick you cut to length and slide in behind them.
it looks like someone knocked the pipe down from 8 to 6 inch. the pipe baffle should below the 90 degree elbow,, just get it under the male end of the pipe. nothing special. 12 to 19 inches.
you need to look upon wood stove common off set instalations. your sides will be like 21 inches clearance and the rear . i believe is 18-19 minimun, to a uncombustable wall. most of the heat will be out of the front and sides and top. one thing i see missing . going into the wall. there is a plate, that helps sealthe gap. by putting even pressureon the pipe. it helps with smoke leakeage. you want that/ then get a non electric stove fan to place on top. and force heat around in the house. you can get maybe 70k btu on the high end. but its probably more like 45-50k on normal running.
