Short Bed VS Long Bed Fleet Value

[GMC71V8]

Like I said, I am not thinking investment however it is probably better than the market nowadays! However even awesome projects need limits on money put into it before moving on to a new project. I guess I am more a purist in the 67-72 trucks. I really want to build a truck true to what it was new and only improve things in the name of safety (disk brakes, suspension, ect). So in relationship to short versus long, what would the end value difference be? (thats why I said on an equally optioned truck like a cheyenne)