An inline 6 in a fwd layout is ubsurd. Volvo did it with the S80 and the transaxle has to be so small, that it easily breaks with any real power. Volvo was however been very successful with the I5 fwd layout.
you can put a v6 in it (1mz-fe, 3vz-fe, 3mz-fe)
Besides the custom engine mounts It all bolts up using toyota parts (trans, drive shafts, clutch, ect)
http://www.st162.com/forums/viewtopic.php?t=1691
that write up is for a 4th gen, but same diference for a 5th gen
You could mate a 3rd gen with a 7m-gte