That kit looks good, but if you really want Z calipers consider that total package he has. He’s only charging $325 for the re-man set. That’s not bad.
R3X GTR calipers are bigger than Z32 calipers. Only the R32 GTS calipers are the same as the Z32. You’re ‘kit’ from this guy wouldn’t work with GTR calipers without using different rotors.