For NSS806 you would be best served by a 10' mesh dish. A7.5 may yield satisfactry results. It may still be borderline on some of the weaker signals. I have heard a few say they have had success with smaller reflectors, but I wouldn't expect great results.
The problem with
c band on a smaller dish is not only the signal strenth but nieghboring c band satellites. The width of thier beam alows for too much cross over interference. Another satellite within 2 or 3 degree can cause 'spill over' and degrade both signals. PAS3r is 2 1/2° west and is a fairly string bird itself.