Also consider how you will handle work that is larger than the machine envelopes and how longer and larger work might be supported. I have had 20 foot long rods (1/4" diameter!) in my 13x40 lathe for left hand threading, and various shafts sticking out the left end of the lathe spindle for several feet, long shafts on the mill table as well. I currently have the mill and the lathe side by side in my shop, in line fairly close together, and the lathe work sticking out out of the headstock can be contained in a bushing in the mill vise and I have run long shafts from the mill into the lathe bore for making keyways and such. If worse comes to worse I can pivot the mill a bit and get essentially unlimited length out both doors. With the lathe I can currently get more than 10 feet out the left side of the headstock and unlimited length through a steady rest and out the door, no plans for pivoting it, but it could certainly be done to allow essentially unlimited lengths, just would have to re-level it after moving it back. Most home machinists seem to be stuck in thinking that they are limited by the size of the mill vise and the lathe chuck to tailstock. My lathe is 13" by unlimited length and the Z axis of my mill goes to the floor, unlimited if pivoted 90 degrees. Plan ahead and think outside the box!