A '40 is fairly simple but it depends on your experience with electrics. If you're not comfortable with it pay someone, it's money well spent. I bought from YNZ (price comparison found them to be slightly less expensive) when I rewired my '38 and was/am pleased with the quality of product. I don't know how much was hype but YNZ told me the resellers (Chevs of the 40s/The Filling Station, etc.), that don't specialize in wiring, buy the harnesses they sell from them for resale. Be advised that the modern cloth covered wire is PVC coated wire with a cloth veneer over the PVC so the overall size will be a bit larger. That proved to be a bit of an issue when running multiple wires through firewall grommets sized for the original wire. If you also replace the grommets with new, more pliable grommets it won't be as much of an issue. Good luck with your project.
