The 6.5 Grendel is alot smaller than the 6.5-.284. Here's a link that shows some cartridge drawings and you can see the differences.
I charge $150 to blueprint a Remington action. My blueprinting method is done with everything based off of the bolt bore running concentric. I use GTR tooling for this and every surface is single point re-cut. The receiver face, internal locking lugs are cut perfectly perpendicular to the bolt bore. The receiver threads are single point re-cut true to the axial alignment of the bolt bore and all taper and out of roundness is removed. The bolt itself is indicated in true in a Labounty fixture and the bolt lugs and bolt face are single point re-cut perfectly perpendicular to the bolt body. There are some out there that claim to "blueprint" an action when all they are really doing is cutting the receiver face and lapping the lugs. Usually making the action worse than what it was to begin with. Before you have your action blueprinted by someone, make sure they really know how to do it so your not having to pay to have it done right a second time.