Anything dealing with King Solomon's Temple - its construction, its features both exterior and interior, its utensils, and the legends connected with it - is of interest to Masons and indeed these themes often figure in the ritual.
The Sanctum Sanctorum is one of those features which play a significant role, but there do not appear to be many details readily available about it, especially concerning its interior and the two cherubim it housed.
Title
1978 - THE CHERUBIM - SOME PROBLEMS AND SOME POINTERS - Bro. Rabbi Raymond Apple.