Ray-tracing (RT) simulators are essential for wireless digital twins, enabling accurate site-specific radio channel prediction for next-generation wireless systems. Yet, RT simulation accuracy is often limited by insufficient measurement data and a lack of systematic validation. This paper presents site-specific location calibration and validation of NYURay, NYU's in-house ray tracer, at upper mid-band frequencies (6.75 GHz and 16.95 GHz). We propose a location calibration algorithm that corrects GPS-induced position errors by optimizing transmitter-receiver (T-R) locations to align simulated and measured power delay profiles, improving T-R location accuracy by 42.3% for line-of-sight (LOS) and 13.5% for non-line-of-sight (NLOS) scenarios. Validation across 18 T-R locations over distances from 40 to 880 m between transmitter and receiver shows excellent RT accuracy in path loss prediction, with path loss exponent (PLE) deviations under 0.14 when comparing measured versus RT predicted power at all T-R locations. While RT underestimates measured delay spread and angular spreads, their cumulative distributions remain statistically similar. The validated NYURay advances RT validation and provides reliable channel statistics for 6G deployment.