You might try the owners club. They would know and probably be a great resource. I knew on of the active members some years ago (a bright yellow wagon with a 390 tri power and a respected showing in the Asphalt Ego Rama). But I haven’t run into him in years. They know everything there is to know. Especially if you’re doing a correct restoration.
Also might be worth a phone call to Addco, the sway bar guys. While they don’t list it now, they may still have drawings of info to make one up. If it’s just a driver, and original isn’t necessary.