Are you sure you want to put linear rails on a lathe ? They have to be super rigid to get a good cut. The Dovetail ways and V type saddle is the best. You can an auto-oiler on the ways.thk rail & ball screws for a x travel of 30 or so inches and 12 on the X. I fiqured it may run between 2-3 k.
BTW, Nice cannons.