That plug is the same physically as the plugs that came in my '72 Nova.
So I'd suggest either you look that car up on Rockauto, or else you could try Autolite 25s or AC CR43TS. Those are at the colder end of the scale. There are a lot of other plugs for the application but I'd start with the ACs. They are a surprisingly good plug in my experience.

R.