Re: 6-6.5x47 Lapua in LA?
I built an NRA course rifle in 6x47 Swiss Match back in 01/02 on a m70 P64. The only issue I had was feeding as the case lacks the taper common to most cartridges. Took a little fussing with feed lips and follower but it eventually worked just fine.
The cases are very similar (identical almost) so I don't think you'll have too much trouble.