If I were to build a 9.3x62, I would get a good bullet mould or two, and cast my own bullets, as the cartridge is well suited for it, even with full-power loads. I would also form my own brass from .30/06 or .270 Winchester brass. In fact, a few years ago I built a Mauser 98 in .35 Whelen; it was to be either .35 Whelen or 9.3x62 and I chose the Whelen because it would also accept pistol bullets, and because Whelen barrels were cheaper.
Lyman occasionally produces a mould #358009 which is a 280+ grain, extremely blunt (single radius) round nose bullet. I bought one of those and use it for my full-power load. I also form my own brass as if the Whelen were still a wildcat, because it's cheaper that way.
Paco Kelly, when he was in Africa, built a '98 in 9.3x62; actually I think he had an Arab gunsmith build it for him, and he also had a bullet mould that he told me was almost exactly like the #358009 .35 caliber bullet. He pulled the bullets from military .30/06 ammo, expanded the necks, and seated those cast bullets over the original charge. He used one of those loads to kill a rampaging elephant with a frontal brain shot.
When Paco returned to the States sans rifle, he built another very similar rifle to replace it, only this time in .35 Whelen because he considered them to be ballistic twins, but he also wanyed to make use of the .35 bullets that are common here.
Don't get me wrong, I'm not trying to sway you from the 9.3 to the .35; I'm just pointing out their similarities.
Tracy