Unknown to you all, I am a Ford man too. I've had....let me count.....1,2,3,4,5! Fords, plus my current one, the EA 5 speed with EB multi-point 4.0L, EF Thermofan conversion and EB XR8 LSD, putting out about 120kw at the wheels and its lowered and stuff.
I've owned that model falcon before. Maybe you should get it tuned, gap the spark plugs a bit smaller to get a better burn.
Thats about all i can suggest really. My cortina used a heap of fuel but that was worked 250 X-flow, mild cam, pacemaker extractors, 350 Holey, sports exhaust and 4 speed manual.
A gasket kit for the carby would probably help things along too.