I also looked into it about a year or so ago. As of then:
You can transplant an engine from one passenger vehicle (VW) ,
to another passenger vehicle, (Sami) ;
So long as the doner is the same year or newer.
So long as the doner smog equipment is also used.
Note that I said passenger vehicle, you may NOT tranplant from Lt truck
to passenger or vice versa. etc etc.
You then (after the fact) get to go through the referee
and have it inspected to make sure everything is there and
working properly.
Unless they have changed something, and as long as you follow
their rules, their SHOULD be nothing they can do to stop you, but
don't expect them to make it easy. I tried to find the refferee
station(s) so i could disscuss it with a referee, and it's unlisted,
they will refer you only when they decide you need to see a referee!
That what I know so far....
BTW most of the hacks at the DMV offices know nothing, unless
its new clean registration or clean re-registration/transfers.
Your lucky if ONE person knows more. What's up with that?