Your best bet is to check out Ross Rifle Restoration. They list a long lee stock replacement set for $375. The other small parts show up every now and again on the various auction sites. Sometimes, some of the forum members are able to come up with a piece or two, if asked. Just be advised, it may not be a cheap endeavor.
Here is their link (I am not affiliated with this company, but have heard good things):
Ross Rifle Restoration
Keep us updated on that!
*make sure the barrel is not cut down either. If it is, I'd steer clear