Vapor lock need help already rebuilded
carborator, rerounded fuel line, changed fuel
pump but still dies then later starts.
Try insulating the fuel line. https://www.amazon.com/Heatshield- Products-204002-Shield-Sleeve/dp/B004GNLGTQ? tag=askcomdelta-20
If your sure it is a vapor lock and not a fuel tank venting problem there is some fuel line wrap that is very good at diverting heat away from the fuel lines, it looks like the same stuff a fireproof suit is made of, the drawback is it's hard to put on and cover all the fuel line.
Make sure the engine is simply not running too hot and if so deal with the cooling system but tennis has a good idea you should check out.
Looking for a Used Chevy Van in your area?
CarGurus has 2 nationwide Chevy Van listings and the tools to find you a great deal.