Red....
Please don't take this offensive but.. You are going to wish you never decided to do this project with this "sander"
I have a buffer that is 16" and has a much larger motor... I use it for FINISH sanding... after I use my larger 250 lb belt sander I will put this buffer on and then do a fine sanding. They do make rough grits for it but the speed and weight will not give you a good "cut" on the floor to get thru the finish. It can be done, don't get me wrong. But then again, grab a 40 grit peice of paper and start hand sanding will work also, the differance is time... You would be better off getting someone with a real floor sanding machine in there. Older floors from that era probably has some finish like Wax or Lacquer.. both are difficult to work with. You will burn up a 40 grit paper in about 25-50 sq ft with a disc sander..
If you do go about it yourself, don't skip grits on sandpaper, It may take something like a 16 or 26 grit, but go in order or you will end up with sandpaper "scratches" that will show in your finish coats.
26, 40, 60, 80, perhaps 100 but with the disc you may not need it...
Spend the extra and get a REAL (professional) grade of floor finish. Minwax is crap IMO and so is most others I have tried and seen from the big box stores...
I do wish you luck... let me know if I can help....
Klingspor makes a 13" disc
www.woodworkingshop.com
Your machine will work great on buffing between coats of finish, get one fine grit screen or a "maroon" pad for this...