Big block fuel economy

so i just bought a 78 f150 with what im told is a 429 from a 69 mustang, i ahve to check the numbers yet but anyways . . . as far as i know the engine is stock except for the 750 holley double pumper on it, this truck is goin to be my daily driver/ work/oy truck using it for towing, mudding,, truck pulls etc, i know im never goin to get great mileage im just wanting to get the best i can, im plan on doin a fulltune up on it and thinking switching to a spreadbore edelbrock, anyone have any other suggestions , wood a different cam, intake or anything help? thanks

The money you spend on the engine will probably never given enough return in savings for the cost of gas. Do whatever you want to the engine because you want it done for the power. The better investment for mileage is a newer transmission with an additional gear to get your rpms lower at highway speeds.
Yesterday I was calculating on if I could somehow improve the car I'm driving from 32 to 39 MPG (an additional 7) for my daily 125 mile commute, at today's local price it would save me $2.44. Most changes you do to that engine would possibly add 4 MPG, not a lot unless you are putting in the miles I am. Though percentage wise it would be an improvement if your starting MPG is 9 or 10. I suggest on the engine getting a base mileage usage and then a complete tuneup.

ok, so as i get into the motor it is a 69 block 385 series 429, and its got the c9ve-a heads on it so about 76 cc chambers i believe, what kinda compression should it be puttin out, i wanna do a compression test before i tear into it, also what kinda power does this thing put out? thanks

and what kind of impovements will be good on this motor im thinkin a cam intake swap, as well as headers, any intakes or cams recommended?