I'm 21 now; I blew my knee out when I was seventeen and converted to off-spin.You're 17? Jeez mate I feel old. I'm 31. I'd love to face you myself. Never faced someone from 6'5 at 80 clicks.
If I were to strap my knee up and come in off my full run, I'd probably be at around 78 or 79 mph because I don't do the fitness work anymore.
Here's some footage of me from when I was fifteen if you're interested:
Also, if you watch my right knee in my delivery stride, you can see exactly the twisting motion that ruined it. Not one coach ever pointed out that it could pose an issue. That's again what I mean about poor management of bowlers.