Easy, cheap, and reliable, do not always go well together!
It sounds like you have, or need a double ended lathe, with synchronized spindles?
You need a system that implements axis gearing, i.e. one axis is geared off the other at an optional ratio.
This can be done with a system utilizing a Galil motion card, or other DSP control system that supports gearing option such as Dynomotion.
Both respective heads would need to be driven by a servo type drive that implements encoder feedback.