Here's what I'd do...
1. park the truck and drive a boring economical car as a daily driver
2. save money
3. get OD tranny, 600 CFM carb, more streetable converter, and a cam designed for torque (a fairly mild cam); the 327 if I'm right is more of a midrange-hi rpm performer. Then, it should get better mpg.
750cfm is wayyy too big for a 327 unless that thing was built to kill.