I know it's a bit of an unusual question on the forums, even more difficult with the recent switch from ECS to VSCCS now so I'm aware some of the search results I've gone through are no longer valid (or for the moment, as I'm sure some ECS members are debating continuing to sign up). I've called Yavuz @ Unigroup and left a message, as I did find a post about someone saying they used the same engineer as Greg from Autosport, but then read that Autosport are no currently doing engineering for the moment.
Once again, it's about trying to find one that has some intimate knowledge on Skylines (or imports in general) rather than picking just any on the list. People also mentioned John Wilson, though that is a little far for myself if repeat visits are necessary. Sorry to be a pain everyone.