sb difference fuel consumption

excuse me my English...

my stuff are: Edelbroxk RPM heads, Air-gap intake, other xcelerator intake, holley 600 dp, holley 750 vac sec, cartr AFB 750. MP cam .528" 284º and I like swap to Comp cams xs268s (adv 268/274, 230/236 @050, .488/.501, 110 ICA) solid, 318 and 340 blocks, 4 speed manual transmission, 3:45 and 2:87 gears.

Before i was thinking to assemble a performance engine.... but now i like switch to a daily driver engine.... and can go to fishing with my father or holidays trips.

¿what would you build... (a 318... a 340... a Stroker)?