Well, theres a few things on this list I would change for mileage concerns.
The MP ignition should be swapped out for a MSD or like multi strike/spark system. The Jacobs I have used before in the past was the best and very expensive.
Example; I had purchased a 94 Hyundia excel, 4 cyl. 5 spd car. 35 - 36 mpg's on a norm, added the jacobs and was rewarded with 40 mpg's.
Ditch the clutch fan for an electric fan.
H or X pipe on the exhaust?
What size pipe? Not more than 2-1/4 I hope.
Headers would help. A minor improvment. A cam swap would be good. Same intake duration and slightly more exhaust.
How's the quench?