Marv and Paul,
Thanks for the feedback.
If I made this cabinet again, I would recommend using a 1/2" thick steel plate attached to the top of the cabinet and include several pre-drilled and threaded holes (10-32 or M5x0.5) for attaching future (yet to be designed) tooling. The steel is important for using dial test indicators with magnetic bases for job set-ups. I had to make a work around with an extension arm but the steel base would have been much better (see Homemade Dial Indicator Adjustable Arm Extension ).
Also, the current lathe, milling head and cabinet full of tooling weighs in at 60.5 pounds so it doesn't move on the bench (see Homemade Lathe Modifications for more ideas and details). Any 25mm dia. column will work well for the vertical milling head and if you can add a 0.250" (or 6mm) mild steel square along the side, it might be possible to keep the milling head more accurately aligned.