What also makes a big difference is throat lead angle. A 3/4 degree or 5/8 degree lead with flatten the pressure curve slightly and can add another 75fps generally, sometimes more.
I imagine a 3/4 degree lead and a canted land barrel would be great. A slight gain twist would also work. The extreme gain twists (such as starting at 1-50 ending at 1-10) tear conventional jackets too much but some BR shooters have had good success with ones in the range of 1-14.25 ending at 1-13.5. If your going for absolute top velocity I would look into all these things, and then coat the bullets with HBN (Hexagonal Boron Nitrate).
As you can see, someone else is thinking about a (FAST) cheytec. But right now my 6.5 Voodoo spitting 140 VLDs at 3475 into 1/3moa groups is keeping me satisfied, oh and did I mention it's mag fed