Here in Denmark it is difficult to get a car through it's test (called Syn here) when any form of conversion has been made unless you have some form of documentation approving it. I am looking at a Datsun Fairlady which has a chevy V8 conversion (the original engine is gone) and I have spoken to my local testing station about it. For them to pass the car I need some documents from TUV or Datsun or perhaps someone else official. Any help here would be great :-)

You are out of luck.Unless there are SMOG regulations to deal with,we can put any motor in any car and don't need anybodies approval.

^ Correct. There are no "official" technical approvals for this type of swap, certainly not from Nissan. I'm assuming you haven't bought the V8 car yet - if so, I'd look for a different car with original motor still in it.

I was afraid of that.... However I do have one other chance which is like Britain where you can have a form for SVA (Single Vehicle Approval) and if it is approved you pay the government money (called afgift) to pt the car on the road and register it with the "changes" It's a pain in the A**E but it can be done. The afgift can be quite expensive though. This process is how a hotrod would be approved and tested. I haven't bought the car yet but finding another in Denmark is not an easy task!! I don't think there have ever been any official models in this country. Who makes the V8 conversion kit anyway?

Conversion parts are built by several small companies. "Jags That Run" (aka JTR) is one that comes immediately to mind. Can't think of the other. But it's not hard to do without a "kit", so that may not be much help either.