5 axis machine from Seig SU-1 Universal Mill

I saw a video of the SU-1 "Universal" mill the other day and noticed how, when used as a vertical mill, the head is built to rotate. Having done conversions on Seig mills in the past, It occurred to me that if one were to do a CNC conversion on one of these, one could potentially affix a stepper to the rotating head, and have a 4th axis without a rotary table, or more interestingly, add a 1-axis rotary table to give you a full five axis rig without having a trunnion table eating up so much volume on your mill.

Just a thought for a potentially interesting benchtop mill project. I couldn't find any evidence that this has been tried before. if anyone has, I'd love to hear how it turned out. if not, if anyone has any thoughts on why this may be a horrible idea, I'd also love to hear that too.