My fish room is in an unfinished part of the basement so no problems with that, the tank stand is just snugged up against the wall anyways and the wall is easy as its just painted panelling on the viewing side (rec room).
However, I wouldn't reuse the tank. I think I'd show the house with the tank in place, then get something set up in the new house if I could get a couple weeks leeway and start up a new tank. My current tank is scratched to hell so a new tank is in order (maybe something bigger too
).