I do not have the 793rd roster, but have a little bit of info about John Palmer. This info is from the "Officer's Semi-Monthly Roster" for the 468th BG when they were training in Salina, KS in Nov 1943.
Marital Status-Name: S-Palmer, John R.
Branch: Air Corps
Date of Rank: 7/28/43
Pilot: P-5-4 Engine
Assigned Per: Hq. Hobbs, N.M.
Special Order 234
I will be going to the 58th BW reunion in Hartford this year and will search their archives for a 793rd roster.