Knowing the manufacturer and model number of the lock unfortunately does not help in locating a replacement key. The majority of historic lock companies are no longer in business.
Lock bits, also known as blades, are specifically cut in a pattern to fit a lock and turn the mechanism.
These cut-patterns are rarely interchangeable as lock mechanisms can be quite complex. This makes it exceedingly difficult to know the exact pattern that needs to be cut for the key to turn the lock mechanism.
Cutting the bit/blade, to turn the lock mechanism, often requires the skills of a locksmith.