"on my '51 chevy the foot pedal will engage the starter and crank the engine over with the key on or off but the engine will only start with the key on"

Same for my 59. In fact I've jumped in put the key in and started talking to someone, then cranked the engine and wondered why it wasn't starting. Took about 5 minutes before I realized I had never turned the key on. Of course, by then it was flooded :-)