Uncut is worth more.

As a locksmith, I have many older key blanks for Chevy's, Ford's, etc.
They sell very well at Classic car shows, etc. Especially when you can generate a key to work a lock that's over 50 years old!

Definately a Nash.
Best,
Scott
PS.
Kracer, you are right. I'm sure it will match up to one of the 6 cut square head blanks, pre VATS...something like a B46? I'd bet that it would fit certain models of Cadillacs, my first impression of the pic. Definitely for the ignition; the oval heads were for the doors and trunk....I don't have my ILCO book handy to compare bitting and would also have to see both sides to be able to tell ALL model cars this key would fit......