Suspect Scott #349, Used Single.
This is a reasonably priced issue cataloguing for $100 as a used single. This coil is often faked and can be manufactured from the following stock: adding fake perforations to a trimmed imperforate #344, adding fake perforations to the imperforate vertical coil #344V, trimming the perforations off the left and/or right of a perforated #332 and trimming the perforations from the left or right of the #332a booklet stamps.
The watermark is telling, it is a double line “S” at the top of the stamp on its side – it reads from top to bottom. This only means that the stamp is from a booklet pane. Flat plate sheet stamps and coils were printed on paper with the watermark reading horizontally from left to right or right to left. Booklet panes were printed on paper with the watermark reading from the top to bottom or bottom to top.
Conclusion: In my opinion the suspect is a #332a booklet single from the bottom right side of the pane with the left perforations trimmed off.
Reference material used:
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