If he's any kind of respectable person to deal with, he would let you have it for 2,500. As I said b4 those old str8 6's are tough reliable engines just not good performers so, as you said you would plan to do, swap it out with a 350 V8 and this would be the cheapest and best way to create a Hotrod. You may be able to get the car for less than 2,500 if you know how to talk price negotability or as my mom says it " Dickering with the price ", basicly look the car over, check the frame and then basiccly just start low like 2,000 and then work up the price, show him the paper but, act nice to him and try to treat him with respect cause, his impression he gets on you could affect his price negotabilllaty. All I can say is good luck and I hope you get it.