best compression ratio street build?

just curious what you think. i plan on buildin a '76 360 and drop it into my 70 dart (904 trans and prolly 3.23 gears). i want to run it on regular gas, get the best mileage and horsepower i can. its a daily driver so mileage is kiunda important in my build, though i dont expect miracles. i assume the higher the compression ration, the better power and mileage.....im not very tech savvy as far as motors go YET so bear with me, im prolly wrong in my assumtion (im only 18! give me some time to go to school for this stuff and ill know better!)

so what compression would ya suggest for a street car to run on regular and get round 300hp and 18mpg? 10-1 is what i hear most but idk if you can run regular with that