rpm airgap vs the m1 single plane

Not sure what youre lower end is - is it factory stock? What gears are int he car?Did you degree that .509?
My suggestions before you replace the intake would be to degree the cam and then advance it 4°. If you haven't replaced the pistons - and the times tell me it's got some compression - look into building a bottom end with decent pistons. The 4200 convertor will mean you don't need (or shouldn't need anyway) that torque. You're leaving at close to peak torque now so lowering it does nothing. You might also want to try a tapered 4-hole spacer on the M1.