I have a 68 3/4 ton 2WD, it had a 327, lucky to get 9 mpg, if I stayed under 2500 RPM. It had 116k on it when I got it and the cam was bad, I replaced the cam before I drove it. It also had 4.56 gears in the rear. I know have a 350 out of a 72 4X4, had to replace the cam, some of the lobes were worn 25%. I now have 3.73 gears a if I keep it under 2.5k I'll get maybe 12 mpg. Late 60s and early 70s Chevy cams are a known problem. Offer him less if it's decent.

Larry

I don't own a vehicle that isn't old enough to drink.