Hello Pete
Here Your's cathedral with corrected bugs in meshes.
1.removed smoothing normals from shadows dead/live
2. removed smoothing normals from collision box for live model.
ATTN! smoothing normals in collision box is fatal error.

Download fm here https://www.mediafire.com/file/ifc6s...r_Ivan.7z/file

If need you can copy collision part from live.msh to dead --just rename it to dead.

BRGDS and HW Andrew (Greif11)