See if you can get the guy to remove the blower belt, spin the blower over smartly make sure the blower at least turns over freely and no grinding sounds. A 6-71 or 8-71 will some times have a ripping or shearing sound if you briskly spin it over. I'd say if it does , it's probably ok. They aren't quiet and the gears will make some kind of whirring sound. Counter clockwise as you look at it from the front. Check out the idler too. It should be free and no bearing noise at all.

Also check out the ignition system . There isn't a lot of room on Chev so look at how it is done. Neat is good.

Headers...blower motors can raise havoc with them so take a look.

When you drive it watch the temp and note if there is an electric fan when it come on and whether it does the job.

You can tell I'd just like to go with haha

good hunting