422 dyno fail

There's more in that with an intake and carb change. Seems to me the single plane intake (and small one at that) with the small carb is really a bit of a mismatch for your bigger inch motor and decent cam. Others on here have built more SB Mopars than me but based on my sample of one 408 build, I think you can tweak a few things and wake it up. Yes, CR is the easiest way to make torque and power so you will live with that. And with iron heads, and if you want to run pump fuel, perhaps you cannot go much higher. My 408 with mild ported Eddie's, a Super Victor with an 850 DP, SFT 251/[email protected] with .560-ish lift, and 10.5 CR crossed 500 #-ft at 3500 rpm. Was the dyno lying? Dunno...but with 1-3/4 Hooker Super Comps and a 5000 actual stall ATI 8" TC in the car, it has run a 1.51 60', 7.11 eighth mile (quarter mile time is compromised as it's geared wrong - 4.56 axle). Car weight is unknown but likely in the 3300# range.
I share just to compare/contrast why I think the intake and carb are limiting you. If my 408 can do this, your 422 can come closer given the 9.2 CR with the right intake/carb. As for the heads, peak flow is not everything. Area under the curve is what makes power as does sufficient bowl volume to draw from. If it was mine, I'd start with an intake and carb change and go from there.