Its on the road!

To keep mileage off the Syncro Westie,  I've got the 83.5 Nine Passenger
/Sunroof GL  legal  and looking good with a nice running 1.9, new Y370s all
around, and a respray to its original white over blue.

Right now the keys are a major hassle. Separate ignition switch key, second
key for the drivers side door and rear hatch, no keys at all for the
passenger front and sliding doors. (The last one is a real bother - because
the 9pax models have a solid half bulkhead behind the front row of seats,
its very awkward to reach around from in front to unlock it from inside).

What is the best way to get back to one key, or even get one to open all
the doors and the hatch?

 (I've replaced a door lock cylinder on my Audi, but in that job I replaced
the tumblers from the old lock into the new. )

Thanks,

Tom F.