Mainly the box to be honest, i know theres some people running high torque through the boxes but i'd rather go for around 350-360ft-lb of torque with a nice curve rather than peak figures .
I think with such a peak torque ,except the box,the rods are also in danger.
Here in Greece we have seen some examples of rods getting C figure
The smoother the t.curve is,the more reliable engine you get.
Are you going to do something with the wastegate(forge?).
Congrats with your project