I don't know anything about the 5R stock, but if it has an aluminum chassis and pillar blocks, it will be good for a build. If it fits good, looks acceptable to you, and has a good price, go for it. Skim bedding will make it better still. If it is a tupperware stock, I'd pass. To me, they're just handles, not stocks.
If it doesn't work out, I've been impressed with the Bell & Carlson Medalist stocks. They have the chassis and pillar blocks, and are less than $300. Heckuva deal.
If that doesn't work for you, get a laminate stock with an aluminum chassis and pillar blocks. In my opinion, that's the best, but will be more expensive. Accurate Innovations makes a dandy, but it'll be in the $500 - $600 range for a plain one. I always use them when I can afford to. If you call them, talk to Wes.
Hope this helps. Enjoy your project.
Tom