WAY back when I bought my Jet GH1340 it came down the interior basement steps in one piece as delivered from the factory. It is actually the lightest weight machine in my shop at only 1200 lbs. It came with the carriage and tail stock pushed all the way to the right as far as they would go, for balance, and had a lifting eye, factory installed to the bed, at exactly the center of gravity. I used a home made cart with 4 swivel casters that I bolted to the bottom of the lathe using the mounting holes of the lathe.
I have to come through the back door right turn down a hallway and then a left turn down the steps. The only lading for the steps is the hallway.
I was able to run a 12,000 lb rated cable from the machine thru the house and out a window and then to the trailer hitch on my 4x4 truck, preset into 4 Lo. I had a snatch block on my shop crane to hold the cable off of the window sill. Used the truck to control the decent. Was a very nice boring move. At one point the machine got turned a bit and the truck had no issue pulling it back up for a second try. This is the same process that I used to move the 1800 lb surface grinder down and the 3400 lb mill down there. I am confident that if I ever decide to move the truck will have no issue getting everything back up the steps.
I did reinforce the steps by laying 2 pieces of 2x12 laid flat and covered with 3/4 ply there were blocks on every step to the 2x12s the ramp was NOT flat onto the steps, the angle at the top would have been to steep and the cart would have hi-centered going over the edge. While the ramp had to line up with the floor at the top it was about 2 feet away from the bottom step. There was also 3/4 ply on all floor surfaces the the machines would cross.
I have since had to replace the stairs (nothing to due with the weights that have traversed them). The new stairs have that angle for the ramp built in and even though the stairs are only 36 wide, their are 4 stringers that were cut out of four 14" lam beams instead of the normal two 2x12s There are then support posts going to concrete foundation under every 3rd step. These new steps will handle anything I might ever want to move across them.
It seems daunting at first blush. but if you have a plan (with contingencies for what might possibly go amiss) and work the plan it makes for a nice boring move, the very best kind.
This was all long before digital cameras so there are no pics of the process.