I will add that if you did or do not flush out the transmission cooler lines really really well, you will continue to contaminate any new parts or new converters and transmissions that you install into that car or onto those cooler lines.
I have used a rod with "some" blue on the big end when there was no evidence of a spun bearing in the journal, I did have it resized though and the machine shop said it was good to go and not to worry about it.
I would just offer to buy the shell from him and be done with it, and make sure if you do that its delivered to your house with a good title before you pay for it.
The newer or older 7 bolt is not too bad, you would want a 98'-99' if you can get one, or even a 93'-94' are decent versions too, but they mount like a 6 bolt would.
I would say that the car is worth what they are asking for it, you wont find many that are that clean, for any amount of money for that matter, some will say that its a bit steep, but find another one for less, not likely, these cars are toys and...