Dirac molecular-orbital calculations are reported for the trigonal bipyramid gallium arsenide Ga2As3 cluster, and comparisons are made to electron spin resonance spectra. The calculations show good agreement with the observed Delta g and Ga-71 hyperfine tensors. This theoretical study predicts both parallel and perpendicular components of the As-75 hyperfine tensors, while experimentally only the perpendicular component was assigned. Furthermore, the calculated isotropic and anisotropic spin distributions show some discrepancy with the empirically deduced spin distributions. The discrepancy between the calculated and empirically deduced values may be traced back to the methodology used in the empirical treatment. The calculations predict that the single unpaired electron Spin spend 31.4% of its time on each axial Ga-71 nuclei, and, 12.4% of its time on each equatorial As-75 nuclei.