I realise this is an old thread, but anyway.
The T2 and T3 turbos are a completely different style. This means you can't simply bolt T2 parts onto a T3 and have it work.
Matching a turbocharger involves a lot of maths and some pretty complex thermodynamic modelling. Or you can simply copy something that works, like taking a junk yard turbo off an engine of similar size and rev range.
BTW T3 frame turbos are/were available in flow ranges smaller than even a T25.