Additional infrared observations of stellar candidates for the radio-luminous type II OH/IR stars found in sensitivity-limited surveys of the galactic plane are presented. When combined with previously published observations, data on a sample of 57 high confiidence candidates is available for analysis. This provides the largest extensive data base of OH and IR properties for the type II OH masers so far collected. The major trends found in the second paper in this series (the trend to higher luminiosity with increasing Delta-V, the trend to increasing maser efficiency with redder color, and the separation of the candidates into two 2-micron spectral types) are confirmed and extended. The data base presented here will be used to develop a coherent picture of the evolution, pulsation, and the nature of the radio-luminous type II OH/IR stars in the fourth paper in this series.