x2 or the cheaper iron block version LT (or is that lz?)
MHO & EXPERIENCE: If you are looking for offroad performance pumping up the 5vz with aftermarket bolt-on schtuff WILL NOT MAKE YOU HAPPY.
Last year I did a JDM 5vz swap into my 3rd Gen. Had my SC rebuilt by the best, Ed Martinez of PSE Superchargers.
URD pulley, 318cc Bosh injectors, Walbro fuel pump and Mallory regulator, and Iridium plugs.
AEM computer and 3-days of dyno time at Church Dyno down in Long Beach.
LC Engineering plug wires & that intake spacer thingy.
Also have K&N type air-filter w/ custom intake & scoop.
It all goes out headers into 3" Bassani free-flow exhaust with an empty cat.
With new dive-shaft cv and U-joints, 4.11 gears it only dyno'ed at 245hp on a wheel dyno, but feels more like 145hp in the seat of your pants. What a joke and waste of wedding money! Granted my runner is a pig weighing in at 5124lbs, rolling on 285x70x17 rubber and automatic transmission.
If anyone has more information on dropping an LS into a 3rd Gen please post up links.