Just from my experance with Celica's and 1G's. They are easy to fit and need minimal mod's for the sump.

A Whole auto conversion can be found for around $600 Gen 1/2/3 and you can add around $600 as long as you run with a gen2 flywheel to convert to man and use your existing box.

There are a million pro's and con's.

At the end of the day it comes down to how much you want to spend,at the tight wad end of the scale you can run a non rebuild 1g for minimal cost. Or a 1GGZE.

If you were going to run a JZ i would run a 1JZ vvti they have a lot better bottom end performance and around a decade newer.

cheers