VaniB,
A 12 twist is on the edge for an 87 Vmax. A 10 would be best. The 8 tw is good for 105, but cost you speed for the 87. I know guy with 1000 Kills on groundhogs with the 87 V max out of a 6mm Rem. I think the 87 Vmax is the best 6mm long range varmint made.
Good luck
Mark Schronce