[moosejaw]

It is not unusual for an 89-93 5.0 to get 25+ MPH on the freeway. City driving is always going to be poor.

My car was at one time a 25+ car. It was before I bought it but it was a good performer. I know it had a 70mm TB, 1.7 rockers, Flowmaster cat-back, and gt-40 heads and intake. The stock cam was retained.

Now I can't be sure the heads and intake made the high mileage combo but the stock cam is the largest helper. Note that the gt-40 heads are not that aggressive. They have smaller valves and ports (than a standard performance head) and are good for mild power and good economy. The intake valves are 1.84" compared to 2.02" for the standard trickflow/afr/edelbrock etc.

Since you want a daily driver, you are correct the gears would not help much. You could leave off the 1.7 rockers and get more economy and extend valvetrain life.

Mike