Z heads? ARE THEY 360 OR 340?

I have never seen Z heads but with Ma Mopar you never know. The only factory 2.02 heads I've seen are X and J heads made before 72. But that don't mean they're not 2.02 valves cause it's real easy to install them. You will probably only know if you remove them and check them. As far as them being any good they all flow pretty close to the same when stock when the valves are the same size.

Like Jomopar said the casting numbers will tell the story. You can find that under the valve covers. You should also find a production date there.