Is there an identity for $\Gamma(z) \Gamma(\bar {z})$?
Post-question edits:
Have you come across any, in addition to the ones listed here? (there, special cases, where the real part of $z$ is integer or half integer, are also listed.)
Abramowitz-Stegun lists the following under 6.1.45 $$\lim_{|y|\to \infty} (2\pi)^{-1/2} |\Gamma (z)| e^{\pi|y|/2} |y|^{1/2-x} =1$$
Since $\Gamma(\bar{z}) = \overline{\Gamma(z)}$ $$\Gamma(z)\Gamma(\bar{z})=\Gamma(z)\overline{\Gamma(z)} = |\Gamma(z)|^2$$