I'm thinking it WILL work on your 80 Z. But you should post pics of the combustion chamber...from a few angles. Get some good opinions from some of the folks here.
That head is either pre...or post, 1982. You need pre 82.
That looks like the right head to me. I think it's a old 50 dome. And I THINK that stamp is from a similar year to your 1980.
Look thru the links below if you're interested.