Unless you paint it yourself your looking at for just material to paint it around $2K and has it been restored underneath? I would make an offer of $1500 because by time your done with it doing all the work yourself you will probably have at least 8K into it. I recently did my Sons 64 Shortwide and it was really nice to start with and that is about what I have in his. Unless he has paperwork to show that the engine has been rebuilt by a reputable Machinest you can bet that engine is not as good as it sounds. The TH350 are a fairly weak tranny and I went through 2 of them until I stepped up and put a TH400 in my Sons truck and haven't had any problems since. Im sure you will have other people tell you different but that is what happened to me so that is what I go on. I am now putting a 700R4 in my Sons Pickup to gain the benefits of the OverDrive. You might want to figure out what gears this truck has in the Diff because if they are 4.10/1 or even 3.73/1 ratio your not going to like it on the freeway. That is the main reason I am putting in a Overdrive Tranny in my Sons truck. It will rattle your teeth at 60MPH because it is reving so high. Here is a picture of my Sons truck completed. Again I had about $8K in it when it was done.
All of what I have said depends on what you want from your restoration and how far you want to go into restoring it. Because I restore these old trucks I find myself more apt to try to get them for less because I know what it takes to get them completed. Good Luck with your purchase.
JRBECK64