you made a good choice by going with the 1-12 twist. You will still be able to shoot the longer bullets. My buddie has a 30" 1-12 twist barrel on his 6BR, and he uses the 95grn Berger VLD wih excellent results. However, for varminting, his favorite load consistits of the 70grn Ballistic Tip with 32.5grns VV-N135. He pushes the 70grn BT at 3550fps and it is deadly on varmints out to 700 yards. He liked the 95grn Berger VLD's, however, when he would hit the varmints, they would craw back into their holes. He said even though he has to adjust a bit more for elevation and windage, the 70grn BT puts the varmints down much better and provides the splat factor that he likes.
I like the VLD type higher BC bullets too, however, they do not have the same kill power as the poly tipped bullets. For varmints out to 1000 yards, I will always try to find the highest BC poly tipped bullet that will shoot in my rifle. But if I am shooting past 1000 yards, than I will start going for the Match Kings, A-Max's, Berger VLD, Scenars, ect. Most of my varminting is done between 50 to 800 yards, so the higher BC bullets are not nessessary.
If most of your varminting will be done from 50 to 800 yards, the Ballistic Tip's. V-Max's, Blitzkings, ect will work perfect, and they will also send your varmints into the air. My new varmint rig, I am having buit, is being designed around and will push the 110grn V-Max and 125grn Ballistic Tip at 4000+fps.
Once again, you made a good choice with the 1-12 twist barrel. You should be able to shoot bullets from 55grns all the way up to the 95grn Berger. Have fun blowing up varmints.