The write up on Twisty's 2nd gen with 1uz is really great. here's the link:
http://www.uzswap.com/forum/index.php?topic=37.15
I have a 90 LS400 with 1UZ and i will highly endorse this motor. I bought it with 165k and 5 years later it now has 240k miles and is the best motor i've ever dealt with in any of my dozen vehicles (short of my yamaha 1100).
good luck if you choose to go this route.