Particles in quantum vortex states (QVSs) carrying definite orbital angular momenta (OAM) bring different perspectives in various fundamental interaction processes. When unique properties arise in the QVS, understanding how OAM manifests itself between initial particles and the outcome in vortex particle collisions becomes essential. This is made possible by applying the complete vortex description for all involved particles such that angular momenta (AM) are represented by explicit quantum numbers and their connections are naturally retrieved. We demonstrate the full-vortex quantum-electrodynamics (QED) results for the Breit-Wheeler pair creation process and derive the AM-dependent selection rule. The numerically resolved cross sections show antisymmetric spin polarization and, most importantly, the OAM spectra in vortex collision processes. The latter reveals efficient conversion of OAM to created pairs, leading to featured hollow and ring-shaped structure in the density distribution. These results demonstrate a clear picture in understanding the AM physics in the scattering processes of high energy particles.