Dom, it should be fine if it's one of these from G-Force. Estimated to handle 600hp/600tq in a "normal weight" car, you'll have a hard time breaking it in a lightweight Cobra unless you plan on having my sister in law along as a passenger on all your quarter mile runs:
http://www.g-forcetransmissions.com/tran_gt-5.asp
I have a regular T5 behind a 450ft/lb stroker in my Unique and I was told to expect an early failure. Well it has survived numerous dragstrip launches and powershifts as well as a previous owner who loved to entertain the masses with 1st and 2nd gear burnouts and smoky donuts.