First approach:
- the leather shell looks good, with 2 holes without grommets
- the spike and its special nuts are good
- chinscales, visor trim, rear spine as well
- as described, the cockade was re-painted
- the plate: The IR 91 was created in 1867: just 1 Regt! So M60 and 67 could have been worn with the Oldenbourg Wappen. According to Larcade, the Oldenburg wappen is the easiest to reproduce. The Prussian eagle could be good (even if its nuts are later). But the little Oldenbourg Wappen? There is the question.
A picture of the back of the plate is required.
Anyway, a quiet rare pickelhaube.
Eric