i done some flying in 727-100 with michael2 mod. it uses fuel more realistic if modded. right by the tables for cruise and descend.

so i can export and send you FSPassengers statistic tables which indicates fuel usage for climb\cruise\descend and time and distance traveled. but it'll be cool for modded ver only. default cs727 uses less fuel for climb and more for cruise, and default FSX fuel planner wrong for modded version. it'll gives you 3-4 times less fuel needed.

i still cant find right way to calculate fuel needed for climb.  and its really depends on climb procedure which i believe i doing wrong. so thats a subject for another question to Lou  :)

very roughly for modded cs727-100, for FL310 cruise at m=0.78 expect to use 7500 lbs climb (totally for 3 engines), +  3500*cruise time for cruise per engine (in hours), + 4000 for descend (at idle for all engines total) and + some for reserves. Climb to FL310 usualy takes up to 20 minutes if close to MTOW.