i've got one too,
sounds like your going to track day it.
have the box rebulit with steel caged bearings available @140 a set and use the lsd from a late 620ti or 820vittesse. the B type Torsen. lots of info on Rovertech.

the std box will fail under abuse the bearings break up and then they throw a driveshaft out. or the diff fails, if your good at 110 on the M1 like mine did....thats the only thing in five years thats failed.
originally i did by it as a non runner i had a klinger fitted and a 2nd hand turbo and its been good as gold since after an inital problem down to the engine builder.

*after reading through its important over 12psi on a t25 it will go bang fitting a bleed valve is a sure way to break it.
pistons are good for intended power but no good for tuning. im not sure if it will last on that t34!

nissan pulsar t28 fits with a bit of fiddelling and gives good results

but the main thing is as above get over to Rovertech.net as that is a v good resource for parts and advice