I think $4,000 for a turn key 302 with the adapter & rebuilt trans is a good deal. But it is as the others have said, got to find the one person that looking for your combination.

The HAMB has a real good classified section, I have sold lots of 6 cylinder & V8 parts on the site. Also RRR (Rat Rods Rule) site has a lot of Chevy & GMC 6 cylinder builders, check them out.