Its either in the steering colum or some wire is rubbing making contact when you turn the steering wheel. I can't remember, is the ignition switch on the '67 in the collar or in the dash? Do you have a clutch safety switch?
Next, if its an automatic, check the park/neutral switch. Then just for giggles...if its p/s, see if the hoses are moving, rubbing on any wires.
Obviously, this is a case of "shouldn't be happening", so you need to look for weird causes. You may need to go to the DVM - voltmeter and do some real trouble shooting!
<font size=-1>[ This Message was edited by: Beoweolf on 10/24/06 8:50am ]</font>
Is the car stock?
Is the battery trunk mounted?
Is it losing ALL electrical power or just ignition?
Does the car die when you turn the wheel while parked or only when moving?
Check obvious things like wiring connetions especially aftermarket stuff and especially don't forget grounding locations. Also give the ignition switch wiring a good jiggle while running. I've seen the pink resistence wire break through fatigue and make intermittent connections among other bad connections.
The engine loom to the coil and coil to distributor connections. If it has the push on factory style check for fatigue looseness and corrosion or arcing/ burning.