you do know that a good smith can easily change the sights on the 317 back to something useful, those fibersights are kinda cool on first impression, but sucky on game in my opinion.
I would try the gun from sand bags, trying to keep the exact same sight pic every time. I would try both Hi speed and standard speed target ammo in that gun and I would keep a very close eye on barrel leading. I would make sure that the barrel has minimum deposits left behind. I have not played extensivly with your gun, but I have seen two Scandi 357's which had severe leading issues and which once cleaned out, shot fine.