The contact at coxlocks you provided is still searching for a suitable blank from which the key can be cut, using my code.
In the meantime, another company has come through and is able to make the keys, two from OEM stock, and deliver from Australia to Atlanta for about $20 US.
Both of these sources have been incredibly helpful, I would recommend either for ancient key problems.
sales@keys4classics.com is the Australian connection, owner is Stuart.
Thanks,
g