If you're thinking of motorizing the quill & head tilt making it a 5 axis machine, you may want to first investigate which CAM software you will use, as most of what's available in the 'DIY' price range won't give you that capability.
Even though the free motion control software will handle multi axis, true 5 axis capable CAM is still pretty much big money stuff.
You would be much better served in the over-all usefulness of your machine by eliminating the quill (which gives you greater rigidity on z axis) and use the head swivel only for manually tramming the head to the table. (adding a 4th bolt to lock the head to the Z carriage also helps rigidity)
If I were to do it all over again, I would put more effort into building a stronger, more rigid, & more accurate machine & less effort into adding the 'cool factor' kind of stuff.

gd.marsh