As long as the transmissions you have are the getrag 284, they should be able to handle the power. The problem is that if you break it or wear it out there are no parts available to repair it.

 

There's someone on GPONA who swapped a 6 speed out of a G6 into a GP. Custom pressure plate, clutch and axles were involved (among other things) and I think he just deleted the transmission codes. He later did a top swap. Pretty sure it was a very expensive project too.

 

I'm really hoping for this to be feasible!!