Got the same stock 360 set up with the next size larger MP cam - 3.23 gears.
Getting 17 MPG at 65 mph.
Get 18+ MPG cruising the farm roads @
45-55 mph.
we have 3.23 gears in the dart. nice efficient 9.5" converter too.. 680 vac secondary carb. once we start driving it i'm sure i'll be able to tweak the carb more.. all i've done so far is take a little jet out of the primarys.