Fork does not look like the full sloping chromed fork with the Peugeot lion pantographs that the PSN's and PSV's from that time. It is most likely a replacement fork. That is why you do not see any evidence of the SV980 fork decals on them.
Hopefully it was not a replacement made necessary by crash damage ( it would be good to ceck the TT and DT near the headstock for any signs of deformation). Only other reason I can think of why the PO might have changed the fork is to change the rake for quicker handling, as the front geometry on the Mid 80's Peugeots with SV980 frame and forks was quite relaxed, with a very noticeable bend at the tips that were more common on older bikes......