I have some experience in this area, having helped to move a 3800lb lathe down to a basement as well as a 7X42 Bridgeport mill down there as well. I then brought almost the entire shop back up those stairs.
We reinforced the stairs, as bringing the 975 lb main column for the mill went down those stairs, and had to go back up the stairs, as well. Everything except the 8' long lathe bed went up the stairs as well. The short story is there are options. The move going up took 2 months to plan, 2 months to prepare for, and 1 day to execute.
I need to express a serious and potentially controversial point. there is NO room for 'opinions' in this matter. Moving things this heavy done wrong are life threatening situations. If you rig a lathe wrong, you can bend a lead screw or injure your crew.
If you are in/near Calgary, I can have a look at your situation, and perhaps help you out.