I really like your 2-6-8-0! The GN had a number of this wheel configuration which were converted to single-expansion. They did have Belpaire fireboxes. The GN were not the first to use this wheel setup, however. Some time ago, before the Mantua 2-6-6-2 loggers came out, I kitbashed a couple of 2-6-6-2's from Mantua Prairie 2-6-2's, but could not actually power the front engine. The Burlington Route, which I model in the 1940-1960 period, had several 2-6-6-2's they inherited from the GN, and a single 2-8-8-2 they eventually rebuilt to 2-8-0's which worked better. The "Q" wasn't much on articulateds, except in the Black Hills of S. Dakota, relying more on ten-coupled 2-10-2's and 2-10-4's and finally in steam on their 4-8-4 dual service #56XX series. I kitbashed a number of these rigid wheelbase engines using Mantua Mikado and Pacifics. Ain't it fun?!