Just got off the phone with the powers that be onthis subject.
As long as the vehicle is USED you only have to meet the 
emissions requirements for that vehicle as of when and where (in the 
US anyway) it was sold.  USED was defined as having more than 7500 
miles on it.  I am currently driving a non-CA '80 Bus and haven't had 
to make any mods to meet current requirements.  But what was 
originally there MUST be there or it must be installed first.
If you have any more questions call the California Air Resources
Board Vehicle Emissions Hot line
1-800-242-4450

> My wife and I may be moving from Florida to California, driving a 90 =
> Vanagon. This van was orginally sold new in South Carolina. What would =
> have to be done to meet California emission laws? The engine has had no =
> modifications that I am aware of.
> 
> Steve Bibler
> biblers@jax-inter.net
> 1990 Vanagon