I am far from an expert and have done similar to your intensions with the rear gears, (gone from 4.11s to 4.56s), but also know that my suspension needs sorting out in subtle or more drastic ways.
I am yet to return to the track to see what the changes are after the swap and now making more power with different heads.
From what I understand, your shift point and rpm through the traps should be +10% of your peak HP rpm. Your shifts depend on your transmission gear ratios and where your rpm will drop to in order to always have the maximum amount of power being transferred. As for through the lights, closer the redline I had read..
With my 4.11s (& 2 speed 'Glide) I was passing through the traps at a little under 6K @ 122mph. Way too low considering that my shifts were high 6Ks and my redline ~7200.
So yeah, I have switched to 4.56s purely to bring up the Rs in the traps (and have also gone from a 3500 to a 5500 converter for more available power off the line). I hope to be passing through much closer to 7K and mid-high 120s with this engine. (Moroso slide rule suggests low 130s but I'm not that optimistic.)
So yes, I agree with your theory, but just want to see that it's not a suspension issue and not gears before you go to the bother.
Your clutch set up sounds interesting and if it's an improvement, then it's an improvement.
I'm not sure how it compares to a clutch, but with a converter, talking 60fts, I found foot braking at the stall speed was much worse than say holding it near 2K where the main metering system was working (carb) and that seemed to allow the engine's acceleration/momentum to hit the converter better for a more aggressive launch (where my 60s still kinda sucked). The left very soft when foot braking at the stall speed.