That bike will need a chain tensioner because of the horizontal drop outs. Its obviously someones project based on the magic gearing of the single speed drive train. Those were 3 by 6, maybe 7 speed drive trains stock.
Definitely talk the seller down because that is bike is worth $100-175.
I think if you're set on motorizing that bike a bt 100 or something from zeda would be a much better choice as the 212 will easily weigh more the rest of the build. Stripped down like that I'd say its under 30 lbs.