The only real differences between a '50's Strat and any "standard" Strat wiring diagram to be found on seymourduncan.com/fender.com or other sites is that all Strats prior to 1977 had a 3-way rather than a 5-way switch; cloth insulated wiring, and a .050 ceramic disk capacitor.
There is a 50's mod wiring that does this when the volume knob is rolled down (from seymour duncan website):
"With the 50's wiring, as you roll down the volume pot, you add resistance back into the tone circuit as if you were increasing the tone pot value. Effectively, you're raising the tone control as you lower the volume."
It is to keep the tone relatively the same as the volume is rolled down. Without this mod the tone lowers as the volume lowers.