sorry for my hugely lazy lack of reply on this!!
the EPS conversion worked out good, ive been using the car pretty much daily since i did the conversion, its nice to be able to turn it up for parking and stuff, though i usually turn it right down low when driving to keep a nice "feel"
i used a corsa "B" (1993-2000) column but i think the corsa "C" one is almost the same - I got a control box off ebay, there are two types though, one has a lot of contoll and the other well... doesnt (steering has far too much assist even at minimum setting) unfortunatley i cant remember any distinguishing features so cant really advise which is which
the only thing i would suggest is beefing up the alternator and making sure your charge circuit wiring is good n healthy - the steering has the potential to draw a lot of current and the ECU cuts out the assist if its not getting enough juice - brown trousers moment if this happens during "spirited" driving - even more so when it cuts back in and you oversteer hugely
this might be usefull if you get a wonky column
http://forums.corsa-b.co.uk/viewtopic.php?f=105&t=14293hope this helps