I believe the bullet you have chosen will be too long for the 6.5 Mag. I tried loading 129gr SSTs for my 2 rifles and the 2.8" magazine became the limiting factor when the ogive was half way into the neck just so I could load them in the mag. That was probably a major reason Remington only loaded stumpy 120gr Core-Lockts in factory ammo. My practice load is 120gr Bal Tips and hunt with 125gr Partitions. Both sit over loads of 59gr of RL-22 and a Fed210 primer.
Have fun with your 6.5 Mag but this round is not very forgiving due to case length vs. magazine length.
George