I would keep it and hook it up, a friend of mine has 4 of these, he paid 20 to 40 dollars from the junkyard, he paid for a similar one to this one ( but exhaust on back ) 30 Dollars, I am sure it's worth more now, the one on ebay is more than 400 Dollars but been there forever, to have one of these act as the primary hot water source, there are few tricks I watched to having these things work PROPERLY , it's not just thermosyphon to a water tank.
I know of three of these that have cracked because they were not drained properly "Ouch ", trying to weld a crack on one of these is not fun !
One option is to have this thing kooked up to an indirect hot water heater, such as the Weil Mclain, or the Amtrol BoilerMate, then you can use antifreeze, and not worry about it cracking in the winter. nor you would get the taste or the smell of the rust build up from the cast iron. You can also hook it up to a hot tub very easily.
Using wood or coal, you can easily fill up an 60 gallons hot water heater in few hours with one of these, in the warmer month,if plumber properly, you can fire it up about twice a week, and have all the hot water you need !