they have the same bore & stroke as a 1uz -so they probably are!!
from what i have gathered, bosto f the c/o motors are due to spun bearings - typically people not changing oil, and driving the car too hard when it's cold (hire car anyone?)
i know that windom's (lexus gs300 over here i think) are easy to find in nz wrecking yards (there were a couple in one last august when i was over there) pity they are not so easy to find over here!!
now - gearbox. i think you need the donor 1mz box bellhousing, as the casing is supposedly the same as the e series sw20 gt & gt4 box, so you can swap the bellhounsing over - this is something that needs to be confirmed of course by extracting the correct info from one of these american or asian guys who has already done this conversion.