There's a company with facilities in Asheville, North Carolina and Atlanta,
Georgia called 'New York Block' that you can get used 300ZX engines out of
Japan from. I called them a few weeks ago and they said that the engines
they get out of Japan will usually have between 30,000 and 40,000 miles on
them. These engines are tested and inspected by 'New York Block' and they
have a short warranty on them too. This company will ship the engine to the
destination where you're going to have it put into the Z car. There are some
laws in Japan that force people to take cars out of service--even when the
engines are in perfect working order. It has to do with their strict
emissions and accident loss policies. They total cars over in Japan for a
lot less damage than we do here in the U.S. They only have a short amount of
time to get the engines shipped to the U.S. to get some dough out of them.
In short, that's where I would start if I were you. I'd request a 1996
engine though. It should drop right into a 1990 300ZX if I'm not mistaken.
Seems like the quote they gave me for a 1990 300ZX engine was around
$1,900.00 U.S.D.

S.T.