There's a lot of interesting stuff that you have done.
Can you post a link to the HMEM X2 upgrade thread that you mentioned?
By any chance would you have photos of the 4x4 column and the gusseted attachment to the base (without the mill in the photo, or else focused on the attachment point)? Did you weld or otherwise fabricate the gussets or were those stock parts?
Also, would you have photos showing the attachment of the mill's column to the 4x4 column?