My Merkur made about 250 bhp when it had a T9 in it. It weighed 3100 pounds. Stock T9.

A stock T9 would survive. But, remember the T5 is the AK-47 of gearboxes.

You need to make the decision based on gear ratios, budget, serviceability, weight etc. I currently don't own a T9 equipped car but i personallt feel they handle more power than people give them credit for. Maybe I baby my gearboxes...