Turbo(s) question

HellvalleyZ

Hey everyone!
Been around the forum off and on, though I'm hardly active on it, except in the classifieds. However, I'm in the process of building a custom twin turbo kit. (Not sure if this is the right section for this)

I'm currently building my sport touring 6 speed manual

Current support mods/Currently installed
Takeda cold air intakes (will be reused with intercooler piping
ZSpeed Stage 3 Super
ZSpeed CMAK CSC Delete
Custom/DIY oil cooler
Custom/DIY fuel system (walbro 450) and return line
Custom/DIY anti-starvation kit.
Stock block (until I full send it)
Stock tranny
Fast intentions 18" non turbo exhaust (will be a restriction at higher HP levels)
And I'm sure I'm forgetting stuff

To be installed:
All necessary custom intercooler piping/flanges
All necessary custom exhaust piping/flanges either mid mount off the OEM headers or custom equal length headers to retain the scavenging effect
R35 GTR intercoolers
TiAL MV-S 38mm wastegates (X2)
HKS SSQV4 Blow Off Valves (X2)
Bosch 1000cc injectors
Flux fuel sensor
SZ Boost Control Solenoid
Omni 4 Bar MAP Sensor
EcuTek
Turbos...... And this is where my issue is. I was originally going with a pair of Greddy Td05h-18g, then I was going to upgrade those to Td06-20g and I eventually scrapped that plan. I've decided to go with Garrett GTX series turbos, though I'm not sure which one will suit my needs.

I also have a Mercedes E550 bi-turbo (read twin turbo) and I love the crazy fast spool on that thing though, the Z is still faster.
So, I'm looking for turbos that have a similar spool to that, while giving me the option to hit 600whp with the eventual build block

I'm trying to decide between Garrett GTX2863r, GTX2867r, GTX2871r, GTX3067r or GTX3071r
Hotside a/r .61, .64 or .73 I believe the .83 will to far to laggy on twins
What I'm looking for is great spool, hardly any lag, with a decent power potential around 600whp, this is a daily and will see light track use.
Why Garrett? Because I can get them reasonably priced

Future mods
Build block

Thanks for taking your guys time to help me, my apologies for any typos as I'm currently at work and it's 3:05 A.M.