If you give me your bore and stroke, compression ratio and the rpm where you want to make peak torque and I can run a math program I use. If you give me your intake valve size and I can get you close on lift.
I may be able to give you an LSA with those numbers but I have to find that math.
It would be interesting to see what my math says compared to what you are thinking as far as duration goes.
Edit: to calculate an LSA I’d also need your rod length.