I had a Maaco paint job done on a 72 bus I had, and it turned out very well
- but I did all the prep myself.  Like others have suggested, I removed all
glass and just about anything else I could remove from the van.  I even
removed the entire interior and drove it from my home (very illegally I am
sure) the 3 miles to the Maaco place sitting on a plastic milk crate in
place of the drivers seat.  It as basically a semi-drivable metal frame, or
so it seemed.  But the effort was worth it - they did a great job painting
it - they just are notorious for doing lousy prep work. So, do the prep work
yourself - its really not that hard.

M