I beleive the only assisted phantoms are mine, Richs old car and now Chris', which isn't yet working under assistance.
Rich and I both went for the Corsa column, because we knew it was possible to make work, loads of rally guys use them, so there's an extensive knowledge base out there.
There are loads of other EPAS columns around, but the problem is a lot are can bus controlled, and so it becomes a bit tricky to make them work.
The corsa column IMO is still a bit on the light side, however this can probably be corrected with suspension geometry.
Best bet is for you to have a drive of one of the cars at Stoneleigh Ken, Rich's old car will be there.