old timer 44

I finally found an SLE quadrasteer 4WD. Love the truck hate the fuel economy. Highway mileage is quite acceptable but in town I might as well be driving a carbureted 454 dually. Has anyone tried an engine build strictly for economy? The last time I did an economy build it had an A series carter AFB and points in the distributor. Mileage was astounding but that is another story. I do not know for sure but I believe the engine to be a 5.3 but 5.3 or 5.7 the build would be the same. How do they respond to a cam change to trap more cylinder pressure at lower rpm. Can you increase compression without going to premium fuel. How about ECM re-calibration. how about cleaning up the intake ports to diminish forming fuel droplets or with injection is this not a problem. And the list of questions grows. I have gone into these things blind before but it usually works best if someone has been there before. I will be diving into this thing eventually, right now I am just looking for general information if anyone has any.