Horsepower with mileage options

The trick to build power with the least amount of overlap you can get away with. Overlap kills mileage but its great at building mid high power. Rhoads lifters can help, same with roller cam wide lsa and high ratio rockers good flowing heads etc...

Compression matters but really our hands are tied with how much we can have.
For a mileage cam squeezing more the 9:1 can be a chore and you definitely don't want less than 8.5:1 if you can help it. So you got a narrow window not to much be done here.
There is things you can do to increase this but you better know what your doing. Going up to 10:1 from 9:1 is only gonna get you an increase of 10-15 hp on your build.

And overdrive is number 1 way to increase mileage on highway. But it also allows the number 1 way of making your car a street terror is allowing deeper gears. Deeper 1st and 2nd might also help.