If you are fixing the truck up to sell you are best to keep it stock.
As much as I like the stock trucks I must disagree with that statement. Check out the auction prices of all trucks, and the modified's consistently bring more money.....I know two places here that consistently deal with old trucks (mostly AD's) and they can hardly give away a bone stock truck. Do a few mods to it, later model engine, 6 or 8, disc brakes and power steering and watch it sell. But then, cletis, by your own standards the truck is not stock anymore.
I guess if they are in uncared for condition or have not been reasonably and faithfully restored I would agree with Alvin. But when I see carefully and authentically restored models, or very pristine originals, I believe they can command value at least comparable to resto-mods or rods that have been as carefully executed. I have no proof --- but I would be interested next time they want to give away one (or more) of those "bone stock" truck(s). 