Is the m1 faster then the air gap

I'd say either the M1 or the Victor, with that gear & stall your into 4500+ RPMs out the gate too 6500 quick, A single plane intake will better serve that window, the only area it would be weaker "down low" is if your cruising around town, which obviously your not lol, try it 1st. without a spacer, i'll bet it picks up ET shifting above 6500 with the single plane from the RPM you have now, thats where the RPM is fadeing off, as long as the heads/cam are still pulling, then start playing with spacers, try open & a 4 hole tapered like a super sucker, you'll still have top end, but it'll help the bottom a bit, then try a larger carb, with that RPM, a larger carb will most likely help too.