I just discovered that apparently the ignition switch was changed on my 1964 Fury not long before I got it. The key that came with the switch works the switch just fine, but has no effect on the door locks. That key (and the trunk key) are all that I got with the car, and now the previous owner is long gone.

Can I do anything with the door or ignition locks to get the key to work on both? Or will I just have to get new door locks and carry two keys, and if true, where to get new door locks? Thanks!

Remove the door locks & take them to a locksmith, he can re-key them to match your ignition key.

I've read that it is not that difficult to recode your cylinder locks (and cheaper then a locksmith). Just a matter of swapping pins around. Anyone know about it? Thanks!

You may need special key blanks and pins to work in a 64..
Mopar changed vendors in 68 from Yale to Briggs and Stratton..
The key milling and pins do not interchange backwards from 69...

The earlier door locks are a real PITA according to my locksmith, and parts aren't available. Be careful if you buy a set, prices are all over the map. Bought a supposed NOS matched set from a place called Jesser's ($245!!) that were in fact not NOS and they fell apart.

1962 to 1965 door locks are a PITA to rekey. Plus the pins are different sizes that the 1966 and later locks. Most of the rekey kits have the later pins.
However I do rekey the early locks frequently. Send me a PM if you want them done.