Re: project help?
Never shot a greybull stock, but they seem to be similar in design to the HS. I have a Mcmillan A5, and am very pleased with the fit and feel of it. I'm not familiar with the borden action, but if it isnt a remington clone, you may be better off with a custom inlet from Mcmillan.
Ive heard great things about the muscle brake, painkiller, and vias alike, but havent shot them. I have shot the badger thruster and was vey impressed. Noise wasnt to hateful, and recoil was very tame. (300 win)
Sounds like a great rig. Good luck and hope I was able to help a little.