340 build - last time I "axe" these questions

Before I call Summit ... here's my plan, would you change anything ? '69 340 .030 over (don't know compression yet) X-heads w/mild porting (haven't checked them yet but intend to) Airgap, TTI's, 750 Street Avenger, 3000-3500 stall, auto w/3.91 rear, manual discs, Dart. Looking at the XE274 and is the 750cfm going to give me any lag issues (would a 650 be more responsive with the package ?) My goal one day is to see mid 12's and I'm considering more headwork or Eddies, stroking's out of my range right now.