Hi there mate-got your email. As for the A340 type boxes, they can be moded to handle the torque (mine is absorbing well over 700Nm now), and MV autos here in adelaide are the guys to speak to. The key to making them cope is supposed to be mods to second gear. The kits from the US have all the re-build bits-but don't have any of the required 2nd gear mods. There is machining required to the main casing of the trans and other bits and pieces involved.
Give mike a call anyway as he's the expert (and a VERY trustworthy and reputable operator). He'll be happy to have a chat and lay out all the options.
For a bit over $2000 (assuming you a install everything) you should be able to have a bulletproof trans.
Alternately, you could go the C4/powerglide trans, but that will involve belhousing mods and you won't have overdrive or converter lockup (mine still has both-great for cruising)
As I said though-mike is a good starting point and has done heaps of work on A340s and converting jap cars to other types of auto boxes (he's even done a powerglide into a GTR-I shit you not-I've actually seen it......)