Took new pictures of this rifle and figured while at it may add them to this thread again since the original ones are anyway lost.
PS: When I just pulled it for taking the pictures I thought of what scope may have been used on this rail. When putting it back to storage I thought maybe the Finns used a Model 1931 top mounted scope ("PE Scope"). Thought worth a try ... yep. Fits that rail. Though I suppose it may had been altered at the rear to be pushed all the way towards the front where a stopping block is located.