The RS35 is perfect for the 7M and has been selling like Hot cakes for Good reason, and being a brand new unit which is Half the price of a similar Garrett turbo (which i'm not a fan of) it's pretty bloody amazing.! Holset are what all the swedes/ scandanavians run on their 900bhp monsters so if you can't beat them/ join them
As for AFM'S, Yeah, they do swap over without any headaches. the electronics are the same, just bigger body.
And some additional info, but you'll need bigger injector's 550's from a mk4 2jz tt
Looks like I'm also gonna need to look for an exhaust system, can anyone recommend how I go about this? I'm guessing it won't be as straight forward as bolting a mk3 exhaust system on there or will it?
It's not as simple as bolting on a mk3 Exhaust, but if you have the turbo down pipe then you can make good use of the flange if your going to use the CT26. The most important part of the system is having it as straight and free flowing as poss. Due to the Turbo supplying the back pressure you don't want any real restrictions so 3" all the way through would be the way to go. However you do it, special consideration is needed for Clearance around the steering column as it's a pretty close fit and can foul.
Material choice is up to you really. Some mild 3" Mild steel tubing will happily do the job for a custom fabricated system, but if you want it to last forever and be a proper exhaust them 321 stainless is the way to go, as unlike 304 it contains a bit of Ti in there so it gets stronger with Heat Cycles a bit like a SR71 blackbird!
I'd put a few flexi pipes in there just to save it from working loose.