I'm 100%. behind that! And in all honesty, the gain from a 650 to a 750 is probably only 10-15hp. And I say That without care to your combo because that is what often is seen.
Every dyno shoot out ive seen with the 6 pack loses to airgap or similar intakes.
But let's be real and honest about a 6pack. You build one because we you want to not because we you need to.
The old as a dinosaur intake holds its own against anything dual plane within its perimeters of operation. That intake is the way of way of gaining power.
Multi carb it!