The 8mm Rem Mag has a nasty reputation of excessive recoil so I wouldn't go to light on the stock. If you want a thumbhole stock I'd look at a
laminate from Boyd's and install a couple of crossbolts as well as pillar and glass bed the action. Search for KG Gunkote or other metal finishes on the web you will find a bunch or people who do it.
CS Sport has a great reputation for doing metal finishes and rifle stock painting.