If you're going to the trouble to pull the dash, I think I would just put a new motor/fan in there.  One piece of advice I can give you is to not order the cheap fan from Bus Depot.  When I had my dash out that's what I used and hate that fan with a passion!  On speed 3, it vibrates the entire floor and dash!  Damn thing is obnoxious.  I'm told that the air-conditioning uses an identical fan, and if I had things to do over again I  would look for a used air conditioning fan. They are not used that much, so chances are good of finding one with lots of life left to it. There's a lot of aftermarket parts that are absolute junk.  Please don't make the same mistake I did!

Might also be a good time to replace the foam seals.  I think I spent a total of about 8 hours on this project, and my only regret is putting in the junk fan.  Everything else was well worth the effort.  Also a great time to clean up the grounds.

Cheers,

Troy