The Chevy part is a Chevy G-series van. Not many shops work on 30 year old trucks, but. you need to be. looking for a good independent mechanic. RV shops usually don't mess with chassis issues. You might see if there are classic restorers in your area who might provide some knowledge. Cevy van has a decent following in the antique and classic community.
You do know, you've bought an antique, by the standards of car collector community and some states for licensing purposes? in some states, it has been an antique for ten years.