Welcome!
Just saw this site on production numbers for all Chevy trucks:
http://outintheshop.com/prodnum.html
Parts are easy to find - many new parts, used parts - under the hood stuff is real easy. There are some stuff that is not around - various body parts - get the LMC catalog and look closely - you can see some trim stuff and various body panels aren't available, etc.
I'd say a nice running minimal rust 5-10K. You see some steals from time to time - but I think that price range is about right. And 10-20K and up for REALLY NICE.