It should hold up just fine.
My Z3 gearbox is rated at a pathetic 250-270 Nm (off the top of my head) and I am running around 500 Nm through it at the moment. Its still in one piece after a year and half since I am not doing drag racing launches with it. The drift guys are the ones that seam to destroy gearboxes at a regular rate.
I do have a 420G from an E46 M3 to go in this summer but thats more for the sixth gear then the power rating.