As for cosowrth management i would recommend Jano on this, anti lag too perhaps

The t3 conversion is failry straightforward all you need for the job is the folowing.

T3 turbo
esc rst - manifold downpipe oil feed pipe and oil drain.off the turbo.
You can then fix a rubber elbow from this to the boss on the block.
The pipe work will need slightly modding but this is possible by modding the pipework you have on the t2.

Thats that fitted, but the hardest or more aggrevating part is to move the rad forward.

You have to decide here to keep the lock mechanism or ideally for safty and practicality fit bonnet pins.

The rad needs to be moved forward to allow the actuator to have room.
Only about an inch or two to be safe.

Other than that its sweet, still run standard map etc.