Intake Suggestions 340 w/One Step above Stock Cam and a Street Demon Carb

Whilst not wishing to contradict the good info above, if I was buying a new manifold I'd go the extra and have an Air Gap. I've always used them on my 340/360 motors even when only a mild build with a XE262 cam. The various dyno articles indicate that torque improves right thru the power band.
Possibly the only consideration is that the AirGap does put the throttle cable and kick down lever higher than stock.