I've been told the Golf AGU engine is one of the strongest twice now.
It's got the stronger crank and big valve head.
I'll be using a K04 as 260-270 is easily enought for me. The 5 speed box from the golf is an 02J which fits - these are rumoured to take between 300-330 bhp. V-dub shafts are hollow which is a bit of a gift come fabrication time, as the clio shaft will slide inside it. Then you may need to put a sleeve on the clio shaft, then weld.
The MK1 I have been researching owned by Flan had a K04 with the standard Audi TT injectors, AGU block, EVO IC, emerald and made 279bhp / 280lb/ft @only 10psi !!
im going MK1
Cos they are a little cheekier
and I don't want the 2010 tax bill