How about the old Comp cams High energy 260? I used one years ago in a 73 Vette 454 with barely 8-1 and 3.08 gears and a turbo 400. It made ridiculous torque, ran 13.80's and idled like a caddy! Performed all out of proportion for its modest specs. As I recall, I ended up getting about 16 mpg on the hiway and the 73 weighed about 4K with my 220 in it. I expect it would be cost effective also.
