That is a lot of scratches. I think those scratches would drive me crazy, especially on a front rim. I would probably look to replace the rims.

Since you mention the scratches are only on one side, my guess is that the bike was regularly hung on a hook with a rough edge.

Just thinking out loud...maybe fill the scratches with bond-o and give them a light sanding to smooth out the surface? Might not look great, but hopefully the scratches are on the non-drive side and nobody will ever see them.

Switching over to new rims is a fairly easy task. And yes, you should be able to re-use the spokes.