A few quick questions, will a 5 speed handle the power of an A14 turbo?
-Is there a off the shelf gearbox Xmember to fit a 5 speed to a 1200 ute?
-Will the shifter come through the floor in the same place?
-Will a 120y diff fit a 1200 ute(don't want to break the original) and handle a locker?

The original diff is stronger or as strong, and you probly want to look for a a63 5 speed or a dellow/toyota 5 speed kit both are upwards of $1200

A few quick answers
1 A series box NO
2 NO
3 A series YES
4 NO,but why would you change it anyway as the H165 is stronger than the H 150 found in the 120y
5 Not an answer to anything but why don't people put thier location when joining the site anymore?

will a 5 speed handle the power of an A14 turbo?

Yes, the B210 A14 5-speed 63-series.

-Is there a off the shelf gearbox Xmember to fit a 5 speed to a 1200 ute?

Yes, the 1200 automatic xmember.

-Will the shifter come through the floor in the same place?

Yes. All a-series gearboxes come out in the stock shifter hole.

re. diff.. I don't want to blow up the original ute diff and then it be impossible to find another whereas 120y diffs are everywhere.
I think the 5 speed i have is a 60? Is there such a thing, i could go check but cold out and cbf'd. if so your saying this box will not handle the extra power..saying that i'm generally fairly rough on g/boxes so a T50 would prob be the smarter option?

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.