If your going V6, don't piss around with the 3VZ. The 1MZ is newer, lighter, requires the same amount of work to transplant and the 1MZ is just as cheap (you can buy a manual 1MZ Camry for $800 - 1500, R&T has one for sale right now). The 1MZ has more horsepower, more torque and you have the option of VVTi on the newer versions.
They are also pretty easy to setup with an aftermarket ECU, I've seen a couple of Adaptronic, Link and MegaSquirt ECU's.