The hi performance intake and exhaust won't show you much in mpg gains below 3000 rpm. As an ecomodder you'll rarely be there, so the current set up is about all you'll need.
If you've got money to burn,I'd first invest in a HEI system to help you get more out of the fuel that is being used. Find an old carburater pro to set up your carb -- maybe run it just a little bit leaner than spec.
Of course a grille block, electric fan (which will almost never come on),and a belly pan are always sure to help.
