Clutch diaphragm spring. How to choose it's diameter?

So first of all - Hi! Now - my question. So i'm doing a project on a clutch, and i am given a light truck vehicle, with a 770~ Nm torque and a 228 kW engine. And i need to design a clutch for that vehicle. So, because of high torque i chose a multi plate clutch, with a friction discs 350mm in outer diameter and a 290 in inner diameter. And know i need to choose a diaphragm spring(or coil springs would be better?) but i don't know how to calculate what diameter of diaphragm spring should be. Maybe someone could help?

So first of all - Hi! Now - my question. So i'm doing a project on a clutch, and i am given a light truck vehicle, with a 770~ Nm torque and a 228 kW engine. And i need to design a clutch for that vehicle. So, because of high torque i chose a multi plate clutch, with a friction discs 350mm in outer diameter and a 290 in inner diameter. And know i need to choose a diaphragm spring(or coil springs would be better?) but i don't know how to calculate what diameter of diaphragm spring should be. Maybe someone could help?

Its been a while since you posted the question so I am wondering if you were able to figure out. I´m just curious to know if you got an answer.

IF you have a vehicle with these specs I could find it with the whole year/make/model or transmission model but by calculating it based on tech specs I am really curious to learn.

So keep us posted!!! Thx!