I have 88 f150 and the engine is blowing white smoke and knocking bad. So i have put the truck away for the winter and am going to pull the stock motor out and build a new one. I have a few parts around to build a new 5.0 but unsure yet what i should build.

part specs: World JR heads ported, 1.6 inch roller rockers, ported stock truck upper and lower intake. Long tube flow tech headers and a limited/ posi track rear end with i think 3:55 gears. The truck has 2.5 inch duals with cats and a stock truck 5 speed tranz and a excell chip for sd ecu

So i would like to build up a engine and keep it fuel injection so its more practcal and i think i should get better mpg numbers with fuel injection.

I have read that these heads arn't much better than gt40's and my goal is to have a truck that i can tour around in on the weekends.

Is it possible to build up a engine and get decent fuel millage and get some more horsepower without sacificing fuel economy. Maybe i am crazy ? If this isn't possible i just want to know what the best engine build is and the best parts to use money is no issue. Any input is great!! thanks