Shawn: You can do this yourself, assume the rails are 4 feet and scale of the picture. I would say 16 feet wide and 6 or 8 foot between the columns, remember this was a temp building so keep it very simple. I beleive that is a “Head Saw” type of mill. I have not seen a kit of one of this type but you can look around, Start with Garden RR and go to Timber times and SHNGG. THere is an outfit, Western Scale Models who have a web site and have a carrage model and a ‘Band Saw’ model as well. I don’t have a site in mind but I would like to build a small saw mill. I would keep it simple but would partly enclose it, Western Washington you know. Ozark has a nice Vertical Boiler power unit, as well as a single ‘spool’ hoist unit. i have not seen a two spool unit, but I am sure there is one out ther some where! Good luck with your efforts.
Paul