S464 vs s467 for compounds

[Strokinbronco]

So I've had my compounds up and running for a little while now and I'm fairly happy with the setup but some changes need to be made. I currently run a s369 / 88mm gt55 combo with 400/200s and I feel that the s369 is just a little lazy to spool, once it's lit it pulls incredibly hard but down low is smoky. I also have to run a larger 1.10ar housing and large amounts of wastegate to keep drive pressure acceptable and I'm worried about the smaller shaft size of the s300 so I'm stepping up to an s400 frame turbo. My question is what would be the better option, a s464 or an s467? I want good spool up but I also don't want to lose a bunch of top end power. I'll also be pulling the stage 1 cam out and putting in a stage 2 and tightening up the housing on the gt55 from 1.23ar to a 1.08ar while I'm fabbing up the new compounds.

 

[BrewTown]

I'm in for the results as I want to do this for my '60 someday.
I have seen a kit offered aftermarket that uses the 464 as the HP, which I'd assume would be the better choice. What is the wastegate setup? Internal that bypasses to the gt55? External may up flow and reduce that drive pressure?
My understanding is that once you add another turbo, the HP one will spool a couple hundred RPM slower than when used as a single. Basically because the pressure differential across the turbine is a smaller difference. I can claim no accuracy but would using that info help you choose? So if as a single the 464 comes on around 1600, expect 1800? Don't claim those numbers as I've never run a 464. Just an example with arbitrary numbers.

Changing everything at once is a great recipe to not know what contributed to what.