Dear All, thank you for your comments and input.

Lancaster. Yes, you're correct, the rifle scope issue could easily be bypassed by changing the scope mounts. However I will try to stick to all-Sako original parts for the time being as mounting a scope with a bigger magnification is not yet a matter of life and death for me; it would certainly have been a nice to have but is not yet a must have. Another option may also be to find original Sako scope mounts of the higher size while I only have medium ones (2 sets, 1 for central tube of 26mm and 1 for central tube of 25,4mm/1 inch), see the below photo (courtesy of Joël Dorléac):

LRF. As already confirmed by Igorrock, rear sights as the one posted above were factory original. The space for the rifle scope probably reflects the immediate WW2-era when most rifle scope were X4 ones, of usual 27cm/10,62in length. When larger rifle scopes reached the market from the early 60's I assume that there was other option but to remove the rear sight in order to make space for modern rifle scopes, see the below link:
https://www.dorleac-dorleac.com/arme/l-46-riihimaki-222-2/?lang=en

Louis