All I'm gonna say on this is that I admire your ambition, but the Trix 0-6-0 needs a LOT of work to be a serious contender on today's N Scale rails. It needs smaller wheel flanges, a better motor, and above all, all-wheel tender pickup. You have seen the reworks of that engine by me and other people on this forum, I'm sure. So you know it can be done. But putting a decoder in there is the least of the complications.