There is something gratifying about this sort of project. Like hot rodding, I imagine, once you're through, you have touched most every system in the car, and it's yours in a way that NIB never is. Nice; one of my favorite locos - I have a Lionel GS6.
A few years ago I found a complete (cheap) - except for electronics and most attachment screws - unpainted MTH Premier NYC Century Hudson and tender. I did not paint it (I did matte clear coat it), and installed an ERR Cruise Commander. I put in bulbs robust enough to take the TMCC boards, hooked up the Protocoupler, found enough screws (some at Ace Hardware) to hold it together and off it went. I skipped sound for now, and left the smoke disconnected in part because of the only clear-coated body castings (the chassis came painted). Very satisfying. Strangely, because of the zinc and the NYC angle, it looks painted, except for the few factory brass add-on details.