A 286 gr 9.3 bullet fired at 2450 will have a near identical ballistic arc as a 180 gr 308 Win. That'll easily get you to 300 yards with very little to no holdover adjustment on larger species like gemsbok and wildebeest and still pack quite a thump when it gets there. Hornady SPRP is a great bullet for that kind of shooting.
If you measure the chamber on just about any 9.3x62, you'll find the SAAMI spec COAL of 3.291" laughable. You'll likely find you can go to 3.32 or even 3.34'.
Not familiar with somchem powders, but I'm sure they have one similar to big game or 2000MR, where 62 - 64 gr of powder will get you 2400-2500 fps with no pressure signs. That's 375 energy in a standard size rifle