I'd bet if you punched that chamber out to the 9.3x62 case and gave it a long throat, you could pick up 300 or more FPS..The 9.3x62 case holds about 8 grs. more powder than the 06/35 Whelen case and the long throat adds a bit more to that, and that 310 gr. bullet should be a hammer of thor...

I use the 320 gr. Woodlieghs in my 9.3x62 at 2400 FPS or a bit more in my long tubed rifle and its a real killer of whatever gets in front of it..