Choose your words wisely, as the wrong words come accross arrogant and condesending.
My input, based on your descriptions, is a head and cam package, and possible intake depending on what the older crate engines came equipped with. I would also look at carb, 625 is adequate, and better for MPG, but a little small for WOT on a hot small block. I would lean towards a 750 unit.
A secondary option would be a basic nitrous kit. Horsepower when you want, MPG and part throttle all the time. A remote bottle opener will cover the argument that you have to get out to turn on the bottle. It could be jetted for anything between 50-150 horsepower.
A 3rd option would be a belt driven super charger. It would stay under hood, and add much more HP at the blip of the throttle, but remain docile when out of boost. It would cost a few HP at low throttle to turn the belt and supercharger, but it would add 50% more HP at WOT.