The lathe is 28" x 144". I turn (rough) 18" chilled iron rolls (3500lbs max) with the lathe, so it would hold a roll stub shaft/axle 2-5"dia, other end is live centered in tail-stock. I finished corrugating them on an old planer. Smaller rolls I turn and then thread\groove the length 8"x55" or so at 8-10tpi (double start 5. I can live with .002-.003 TIR, obviously the less the better. If I can grip adequately with the 3 Jaw then I don't have to change chucks as often. The 4 Jaw is just that much bigger to deal with on this lathe. A jib might be nice. I have a 3T rail but its lying on the ground so far. I currently use a forklift for loading work pieces but its a bit cumbersome for chuck work.
My previous lathe was smaller, old(babbit) and worn out and so the roll size was limited to 12". I used the 4jaw in this case, it never came with a 3jaw until the W&S one was acquired. I never ran rolls with it the (3jaw) I don't think and if so they were limited to 1200#.
The new to me lathe allows me to do all of the sizes I deal with except the 24"ers.