I happen to see your head scratching on the 3000lb lathe.
I used a pair of 1/2 inch wall 4x4 angle iron "tracks" to slide my machines down the basement steps, nothing over a thousand pounds though.
I don't think this would be suitable for your situation but, I also considerd replacing the basement steps with a platform elevator run by cables and a winch.( wife said much on the subject... all of it bad)
I believe Harbor Frieght sells somthing like this.