One thing I tell people that are teetering on the restore/improve fence. Only make improvements that can be changed back. Keep all original parts and pass them on to the next care giver when the truck is sold. Because it will be sold or given to someone else eventually. The next person gets the advantage of making up his/her own mind towards originality.
You can change to 12 volt very easily and put it back if you want. There is nothing wrong with 6 volt. My 1940 is still 6 volt and runs and starts just great. The key for me was rebuilding the generator and starter to like new and it starts very easily. Bad parts usually make people think 6 volts are weak. It isn't. It is just lower volts with a higher amperage. The higher amps running into the cab of the truck is what should make people think twice about 6 volt.
A 51 already has decent brakes, but you could easily convert to disc brakes and an open drive rear end with out altering the truck from original looking.
Use the resources of this site and the vendors that are out there making it easier and easier to make a truck that is exactly the truck you want. Imagination and money can make almost anything.
Have fun.
