starting a car without a steering column

Sure, just "hot-wire" it. I had to do that to drive my 64 Valiant home since the key switch wiring was goobered-in and some spade terminals fell off while driving. Run a jumper from BATT+ to the upstream side of the ballast. If you have the dual ballast (I think not in 1973), that is the side w/ the short jumper between the 2 ballasts. Don't leave that connected >5 min without the engine running or it may overheat the ignition box or coil. To actuate the starter, apply 12 V to the terminal on the starter relay that the yellow wire (most cars) connects to.