I'd suggest that you try this guy-
http://www.everydayxj.com/
His name is David Bognar (hope I spelled it right). He makes a market in used Jag parts, focusing on the xj6.
He should have a good, serviceable LHD rack in stock that you wouldn't have to rebuild. He's well equipped to ship parts too - you'll have to ask him about NZ though.
Best way to reach him is via email on his website. He's always returned my emails within a day or so. He's a 'man and a dog' operation and very pleasant to deal with.
Barring everydayxj, I have an acquaintance here that has a Jag parts collection bordering on obsession and he'd have a XJ6 or XJS rack. LMK if David doesn't work out and I'll put you in touch with him.
Phil