You're not risking much by buying it. Ask a local junkyard how much they'd give you for it as scrap. It's probably a large percentage of the purchase price.
I'd prefer a 5MT and fuel injection. I also prefer manual steering and low rolling resistance tires, but this truck is good for a $400 set of wheels, especially if you won't be driving very far this winter. Do the math on your fuel costs before you buy any car:
http://www.fueleconomy.gov/feg/compx2008f.jsp?year=1987&make=Chevrolet&model=S10% 20Pickup%202WD&hiddenField=Findacar