I have three books that have good discriptions of pit saws..
"Ancient Carpenters Tools" by Henry C. Mercer
it covers mant tools but has a sectiom about saws and frames in history There isn't a lot of practical info. The illistrations are from Diderot's Encyclopaedia. I havent seen it but know it has good illistrations. "The Woodwright's Shop" by Roy Underhill Excellent photos showing both a pit and a frame. The frame in the Underhill book looks good and not too difficult to build. Check your library for this one.
