This record presents the S64 Metrological Framework (Version 2.0), a comparative statistical investigation into a hypothesized modular base unit of u = 64 mm within megalithic architecture at the Giza Plateau and Puma Punku. Utilizing a u-variation sensitivity test and binomial p-value estimation, the study identifies statistically significant clustering at rational multiples of 64 mm that remains robust against stochastic noise. The framework is strictly descriptive and excludes functional, technological, or teleological interpretations. A standardized in-situ replication checklist is provided to facilitate independent verification by the scientific community.