Best cam for the street both power & sound

A fun thing to do if you can find good info is, look up MPG of say a 1970 318 Swinger then compare it to a Swinger 340. Could even look up a 69 318 Satellite and compare it to a 383 Roadrunner etc. Rumour is The Dart Swinger 340 in 1970 got 13 or 14 MPG as a new car ...unacceptable wouldn't you say...?