Retrospective Plausibility Assessment and Constraint Check for Convergence Archaeology Activation Criteria at the King's Chamber of the Great Pyramid

The Great Pyramid's King's Chamber represents one of the most materially precise, geometrically confined, and culturally significant stone structures ever constructed. While traditionally interpreted through symbolic, funerary, and structural frameworks, its physical configuration also makes it a uniquely controllable natural laboratory for evaluating coherence-field hypotheses in ancient architecture. This study presents a retrospective empirical evaluation of Convergence Archaeology (CA) using previously published acoustic, electromagnetic, material, and geometric datasets associated with the King's Chamber. CA predicts that intentionally engineered ancient field systems, where present, exhibit multi-band, multi-material coherence architectures in which geometry, lithic composition, and cavity topology function as coupled frequency-behavior layers. We re-analyze archival measurements of chamber acoustics, shaft geometry, granite material properties, and documented electromagnetic background behavior under CA's falsifiable criteria. The analysis evaluates whether observed resonance structure, directional modal stability, and wave-guiding behavior exceed what would be expected from generic rectangular cavities or ordinary material assemblies. Archival reports describe narrow-band resonant features, axis-consistent modal descriptions, and qualitative signatures potentially indicative of multi-layer coupling beyond purely geometric cavity effects alone. These elements are compatible with CA activation criteria under conservative assumptions, but insufficient for confirmation without synchronized modern instrumentation. The findings motivate targeted, pre-registered, on-site multi-modal measurement as the next step for CA validation.