I stand corrected on the x member,however i stand firm on the other points.As they say"the proof of the pudding is in the eating" and i have eaten a few.
I still think the H165 will handle the turbo,remember half the ute's with CA turbos still use this diff.
Another option would be the 120y borg warner,although i have no first hand experiance i'm told they are as strong as an ox but you have a width problem to be corrected.
Personally i'd sell the 5 speed for about a grand(if you need the money)and fit a Toyota box.