I'm gonna go out on a limb and go ahead and say this out loud: I'd pass on that and keep looking for something better.
The price for something in that condition is too high. Especially for the age. You can find better rollers (i.e. no motor) for a lot less. Just have to get out and look for them.
I'd bet you could find a better shape rig with little to no rust and no motor for around $500.
Thats the feeling I get too. Its level in some pics and not in the other, parked on a hill, whatever, look at the trees compared to the roofline of the truck. More like broken. In addition the bench seat which was not even an option in those years (was it ever in a blazer) It just looks seriously hacked together. Of course if you can get him down on the price and part it out for what you have into it then you could just keep the top and windsheild frame. Finding a rust free newer truck is alot more likely
I hate not having a truck to drive. 
