Within the Z realm....from what I understand....any 5-speed through 1983 is a bolt-on. I would suggest you try to get a later one...as the gear ratio is different. I did the same thing...but I used an earlier 5-speed...which is like a 4-speed with an extra higher gear. The later ZX trans. has a different ratio....first gear is lower, for one thing.
But you will be pleased with the swap! It makes a big difference having that higher gear!