super six or 4 brl?

The 225 in my 73 Dart I am putting on a 2bbl just for better mileage and maybe a little performance. The 225 that is going in Nikkis 48 chevy is getting an Offy intake, Holley 390, headers, ported & milled head (haven't decided how much to take off yet) and a cam at a later date. The 48 will be her daily driver so It wont be a super go fast motor.