The 6.5x70 R was developed to about equal the 6.5x58R or 6.5x52R (aka 25-35Win.) for hunting Roe, but in very light KLBs and combination guns. The cases are a problem; I have a couple samples in my "pile". About the only case I could use as a donor would be 6x70R Krieghoff and I don't have a reliable source for them. I guess the 6.5x70 could be re-drawn from 5.6x50R but I don't have the ability and am not sure the 5.6 can be re-drawn to 70mm anyway. The bullet for this cartridge is not usually .264-5", rather it is .260-1". My 6.5x48R and 6.5x58R both use the smaller bullet, so I'm already in good shape for bullets. I think if I could find a super light KLB in that caliber; I would battle the case availability. Otherwise, I think I'm too old to make it worthwhile. A young lad like Raimey may have enough time left to take such a project on.
Mike