Well I've heard of E153s handling 600hp with no problems so I think you'll be right there. It's got better ratios and maybe a limited slip dif. The S54 is cheap but is probably at its limit with a 1mz.

 

Gearboxes are generally rated to a torque, not HP.  I dont think you will have issues with a 153 box.

 
Cheers guys - really am looking for an actual torque rating, in terms of numbers, for the "engineering" of a V6 turbo conversion here in WA...  Anyone?
 

Maybe on wheels with a factory rolling diameter...

A bit of progress at last. Buying that black SW and a couple of unexpected interstate trips for a funeral set things back a bit.
 
Picked up a recently rebuilt S54 w/ cusco lsd from Melbourne over the weekend and fitted it today. I've gotten 3 of the 6 bolts in. Gotta enlarge one bolt hole on the gearbox and drill out two new holes on the bottom of the engine as per this pic
 

 

http://i.imgur.com/DQTbP.jpg
 
Well this is where I'm at now, gotta figure out how to get atleast one bolt fitted at the bottom I think.

Here's what I ended up doing, I'm very happy with the result.
 

 
50mm bolts. Too long but it's all I could get

Nice post!

 
Hmm done a bit since I last updated this
 
Engine's in the car. Fitted the Woodspot 3VZ mount. Didn't fit funnily enough but Paul's a good sport and has made one with the dimensions I've sent him and will be selling it as a specific 1MZ mount. Yet to receive it though... pay 60GBP for two day postage and it's been a week...
 
Cooling system had to be crossed over. Made new lines by cutting the hardlines under the body and using mandrel bends and random hoses to cross the LHS to the RHS and vice versa.
 
New fluids all around
 
Re-routed some vacuum lines
 
ECU is wired up except for the ignition. All the sensors are working as expected.
 
Fitted a K&N enclosed pod
 
Hooked in a 'genuine' SARD FPR
 
hmmm what else?

Oh and I'm moving back to Adelaide on the 23rd :D

So I'm back in Adelaide. Car's at Classic Performance getting a AFRs mapped. It's taken them over two weeks now but they had their dyno room floodout last week . The car's fine and is currently putting out 141rwkw without the variable intake runners hooked up. Potentially looking at 150rwkw once they're finished with it.

Sweet, glad your car is okay, 150rwkw is awesome considering it's like 140s at the flywheel stock (right?)