I could be forgetting something, but I'm pretty sure the older ones are ambidextrous as well. However, the wires have to be routed differently and/or extended. They should mechanically mount in either position, from what I remember, and electrically, they should be the same as long as you know which wires to substitute (black with yellow, and blue with red).
So you can use two 1/4 or 2/3 pickups on the bike, and just re-splice the correct wires.
here are some photos to get an idea, just imagine the taking the two little mounting screws off the actual pickup (for 2/3) and rotating it from 3 oclock to 9 oclock. The wires will be pointing up instead of down, but you will probably want to use different colors so you will just make them longer.
home.comcast.net/~loudgpz/GPZweb/Ignitio.../PickupAndRotor.html