[658Chevy]

Replace the trans with a 6-speed manual. Get one with a steep 1st gear (2.97) and deep overdrive (0.62). Then put 4.11's in the back. That'll put you at ~ 2400 rpms at 75 mph for the highway. The steep first gear will get you off like a rocket, and the four inbetween gears will keep that little engine in its sweet spot.

 

[658Chevy]

It'll cost him lots of money.