Make sure it's not a city bus, IIRC, they had 6v71 and two-speed automatic transmisions. 6-71 is OK, two speed auto not. All used buses have recently rebuilt engines, which is only believable with proper documentation. You can read the date code on the tires and see how new
they are. That bus looks rough,and probably worth only scrap value. A lot of sellers just want the thing gone, others wait for the fool with money (which I've been a time or two.
Go look at, have him start it, and go on a test drive. Good luck.