I have used these guys on a few occasions and everything they have done for me is great and working fine today, 30,000 miles later at higher boost, zero play in the shafts... Good value for money and conversation over the phone, even went to their workshop one day to take a look and there are 1000's of turbo bits everywhere, proper hands on engineering machining etc...
http://www.turbodevelopments.co.uk/
This includes total standard rebuild of a T28 turbo that spectacularly failed. And on another occasion customizing a standard T28 with 360 thrust and other bearings and something to do with the exhaust side, I can't remember the exact technical speak...
They arrange couriers to and from you if necessary. Think the expert bloke was called George, been in motorsport for a long time. Give him a call!
Cheers,
Adam