Hi EAG:
Yes, you can bypass and jumper your way out of almost anything, BUT: let's do a little logic here.....Does the car still have its original 1951 wiring harness? If so, take a good look. Is it stiff and brittle? Can you see any bare wires? Will pieces of insulation flake off with just a little flexing? Do the headlights go dim when the engine goes from road speed to normal idle? Again, is that wiring really 73 years old?
If the harness has been replaced, was it done right? (i.e. with the appropriate gauge of wire) or a slop job by someone who didn't know what they were doing?
Remember the name of the game with 6 volt systems is current, and the more current you are trying to draw, the more deleterious the effect of a given amount of resistance will be.
Worn, frayed and oxidised wiring will have more resistance than wiring in good condition. And it matters: for example, if you draw 12 watts from a 24 volt system, you're pulling a half amp. (24x.5=12). It will be one amp in a 12 volt system (12x1=12) and yes, you can see where this is going, 2 amps in a 6 volt system (6x2=12). Lots of folks will switch out their 6 volt systems for 12 volt because they use wire of a gauge specified for 12 volt systems, because that's what you'll find at the auto parts store. Things will of course, work poorly. Six volts will work just fine when done right. Clean. tight connexions are a MUST. NEVER use those auto parts store battery cables! Triple ought is the way to go!
So, my advice to you would be yes, check the ignition switch, but don't eff around, rip that harness out and replace it. For functionality, peace of mind and safety.
These harnesses are quite simple, I've made quite a few, and with modern insulation you can go up in gauge (down in number) with the same thickness, giving you even better current handling. Supplies are available from Rhode Island Wiring and YnZ's Yesterday's Parts. They will also make the harness for you, even going up in gauge and with original style colour coded cloth coverings if you should so wish. Expect to shell out some buckaroos if they make it for you, though.
I bought my first harness some 30 years ago, but after that I made my own. The process is quite easy, actually: you stretch out the original harness on a board 3 or 4 meters long and duplicate the lines one by one, keeping track of your colour codes, of course. You will want a volt-ohm meter at your side. You can also use the opportunity to add wires that might not have been there originally, such as for turn signals and back-up lights that you will want to add in the future.
Hope this helps.