http://www.littlemachineshop.com/Products/products.php
For mini mill Porn.. you can make your own belt drive or just buy it like I did. the column is made for the mill and available at the above website.
The longer column mod is a longer z axis rack, and I had to remove the spring that provides the head tension. thus the Counterwieght. (Been awhile since I had done that mod. LOL I got another few inches out movement out of the head that way.
There is back lash on 2 of the 3 Axis, But it is adjustable. the Vertical (Z) is negated for the most part by the counter weight, and you just have to be aware of it. I did work on the ways some, but they where ok. The backlash is the big reason I am going to DRO then if anything moves you know.
I have a 50's Logan 10" Lathe myself.
I did the internal mods to my 1919a4 with this mill. (definitely glad I had done the mods..) And that was milling hardened gun steel. Worked fine within it limits. works great for aluminum, and If I ever come up with the coin for a decent boring bar set up and hones I can do my own cylinder boring on smaller engines.
For the space limited like you and I these are very usable tools when the Limitations and problems with them are addressed. Beats the heck out of a moto-tool and files.