Found some more pictures of some work I did last week on levelling the mill. It turns out the threaded holes in the bottom of the casting are 1/2-13 which makes finding levelling hardware easy. After chasing the holes with a tap to clean them out and making sure they were well oiled it was time for the levellers.
I bought this set at Amazon, but McMaster's and other sources have the same thing. Very nice quality and make machinery levelling a snap because of the ball at the bottom of the thread.
Used the big Starrett level to get things right. Mills aren't like lathes were you have to worry about twisting and such, but it's still nice to be level with the world for some setups or to keep tools from rolling off the table. You can also see how ridiculously crooked this floor was poured. Oh well, I guess it's better than dirt. :)