A BLI T1 was highly converted for the build. Front steam chests moved back, front chassis cut off, rear chassis cut shorter both for clearence for six wheel trucks. BLI T1 tender chassis extended. Built this one for my buddy that has the Ebay store. T1 he bought and sent was a rebuild from BLI but ended up not being so. Decoder fried when he first got it and was remover before sending to me, so I couldn't test run it after building. But it was sent to another friend for a new DCC as well as sound. This video is what our friend sent to me after his work. He did find that BLI's rebuild had two tender axles put in backwards blowing decoders. Also had a bad motor which he replaced with a Kato duel flywheel motor. I built this one using my Oriental Brass one for the build.
For being called the "Standard Railroad of the World", this was one of the most non-standard steam locomotives ever conceived. Your model looks great! This cements 3d printing as a key modeling tool.