In Texas, it is not totally necessary to go to 6 volts because of the mild winters, but I would go to 12 volts anyway. The reason is, these vintage generators, regulators are getting more expensive and harder to find repair stations that fix them. Then there is trying to keep the regulator adjusted so it does not over or undercharge the battery. I realize this isn't terribly hard and there are those who love their 6 volt systems, I am just not one of them. So this is what I do (and have done many times)...
1) Get a 42 amp Delco 3 wire Alternator. This replaces the generator and regulator because it has internal regulation. No fuss, just get the proper bracket (from Classic) and install it. Stick with 42 amps because your stock Amp Meter is a 50 amp max Ammeter.
2) Do NOTHING to the Starter.. 6 volt starters work fantastic on 12 volts and actually turn the engine faster and last just as long.
3) Inside the cab there are a few things to do:
a) Put a 6.8 volt Zener Diode in the power line going to your Fuel Gauge. The part number is available on my website and for less than a $1 you have that problem solved.
b) Get a 12 volt to 6 volt reducer for your Heater System. Classic sells them.
c) If you have any other accessories, get another reducer just like the Heater one to power it.
4) Change your light bulbs and Headlights.
5) Put a Ballast Resistor in between the Positive Side of the coil and the Ignition Switch on your firewall. Everything else will work just fine on 12 volts.
References for how to do all this and part numbers for everything involved are in a few places on my website.. here is where to go:
This one explains how to do the upgrade better than described above:
Making Your Vehicle Native 12 Volts!
This one is a complete re-wire of a 1953 with 12 volts:
AD Truck Wiring Made Easy!
No offense to the Keep It Stock guys. Living in Kansas out on the farm, it used to be standard practice to go get the 8v tractor battery to get the truck started in the winter. I am DONE with that. I realize the causes and I know a properly maintained 6 volt system will keep it running, but for a Parade Truck? No way. You do not want to be stuck in a Parade Line and have insufficient power. IMHO