You might find some parts at Numrich GPC.
As far as scope mounts are concrned, has your rifle already been drilled and tapped for a side mount? If so, it might be for the Weaver #2 side mount base.
If it has not been drilled and tapped for either side or top mount bases, I would think long and hard before I took that step.
Doing so would destroy it's originallity and lower it's overall value.
If it has already been done I would opt for Weaver Top Mount bases. Rear #12, front #31. This would give you many more choices of rings for mounting scopes with large objective lenses. If there are already holes for a side mount, they can be blocked with plug screws.