That's a good looking piece of machinery. I hope you get it moved without any mishaps. If you'll pardon my bluntness, I think you should re evaluate your original thinking. Your concern is somewhat misplaced. Whether the leg will take the side pull of a sling pulling on it is a very small concern compared to not giving enough concern about the whole idea of tobogganing that thing up the back of a roll back. You are only going to get one shot at doing it and not totally destroying that magnificent lathe. I've moved many, many machines. I've got over 40 machines in my shop alone. Several lathes, from a 42" swing Boye and Emmes engine lathe to a double E Monarch. I've been fortunate to not lose any to rigging mishaps. You have to plan the move and be methodical. Them lathes will go over fast and once they start, you ain't stopping it! A good stout skid that is wide enough to preclude tip over is great. Use at least 1/2" bolt with washers under the head of the bolt and the nut. Counterbore the holes on the bottom of the board so the head is not sticking out and even a little deeper. My personal favorite is full size, rough cut oak 2" X 12" with cross ties. Cut angles on the ends of the 2x12 skids so they don't catch on things.
Oh yea... The leg should be more than stout enough to allow you to pull on the lathe
