mx5cartalk.com

NB6 was sold in the UK - tried UK sites? It was also sold elsewhere in Europe.

Not sure if you've seen these posted by a Forumite who put a NB6 into his NA6:
viewtopic.php?f=29&t=29920
viewtopic.php?f=29&t=31023
viewtopic.php?f=55&t=34007

I think Richard at MX5 Plus in Queensland has done this conversion, might be worth giving him a call.

You didn't know about the solid lifters when you bought it? haha. I went with the NB6 to get away from damn HLAs, then what happens. I get another car that still has HLAs...