I'm not sure what you mean by driving extra weight? When I use the set up as a rotary/-indexing lathe, I use a NEMA 34 stepper (260 oz/in) with belt and timing pulleys. For now I use a motor from a rotary tool with gear reduction (belt and timing pulleys) to do lathe work. I will admit up front, I am not anywhere near my level in CNC lathe as I am in CNC mill. But that's only because I don't do it very much. At my day job, I design, develop, and produce proto type infrared cameras for a small company. I take the electronic components and draw them into my PC, and then design the housing and all the brackets, etc., around them. Then I just machine from my cad drawings.
Ken