DD:
A lot depends on the weight of the finished rifle.
Also your choice of 650gr or 750gr bullets.

I can confirm that a 650-grainer at 1850fps needs more than 10-lbs of rifle to shoot comfortably!
A full-nitro 750-grainer at say 1950 fps probably needs 11 to 12-lbs (or 13..!), and may still be brutal if all the weight is forward of the mid-point.

Here's a bit of info from my experiences with a 10 1/4 lb double rifle in my custody: .577x2 3/4 Load Development

Terminal ballistics on buff described here.

Hope this is of some use in giving you a starting point.
There are more loads listed in Graeme Wright's books too of course.