My favorite for a mild 340 is the 71-72 Thermoquad intakes. The LD340 is a fairly close copy (with soem minor changes) of the '71 intake in aluminum. The Performer and facory AVS are much alike, and I dont think you'll see any gains by swapping them. The RPM is a step up, but may interfere with cold air hood setups if this a factory car with that. Another thought might be the Summit knock off Chinese air gap. A slightly smaller port than the Edelbrock Air Gap.