Speaking from experience, I wouldn't go to great lengths worrying about what reamer to use. Stick to the 'standard' 6.5x284 Norman version and press on.
The SA M70, with the proper mods will handle the 6.5x284 quite well. Again, speaking from experience, replace the mag box and follower with one from a M70 WSM. Likewise, replacing the bolt stop with one from a WSM doesn't hurt.
I've had 3, 6.5x284s (Norma). 2 were built on M700 actions - 1 LA, 1 SA. The 700 SA version (as a repeater) never really performed the way I thought it should. As a single-shot, it did well. The 3rd 6.5x284 was built on a SC M70 SA, with the aforementioned modifications. Functioned and fed well, and was a solid performer. The added magazine length of the SA M70 over the 700 SA DOES make a difference. In the end, someone else decided that they NEEDED the m70 6.5x284 more than I did and it has a new owner. The LA M700 6.5x284 is still under my roof.
