Don't know if you can view projects as a forum user. But this is an example of a sorted F7R (williams block) turbo.
http://www.cliosport.net/forum/showthread.php?t=324019
This engine will be good for 300 odd bhp, at which point the gearbox would very quickly remove all it's toys from the pram.
Bare in mind this F7R is really well sorted. It's been previously owned by a company who designed a turbo package. The engine has been properly chemically cleaned and the oilways sorted (oil is always a big issue when going turbo as im sure you know)
There are no current projects for the 480 1.7 block, but it's an easy install. Power output wise, I have no Idea what the bottom end can handle "as is". 200 bhp is a good point to aim for.
The main problem, and the most annoying limiting factor of renault engines with big power outputs is the gearboxes. For instance, running around 200bhp thru a valver GBox and you'll have swarf in the Gbox oil you drain out. Williams boxes are stronger, and 172 boxes stronger still but none are as strong as most of the boxes that VAG make for similar displacement engines.