When the above listing image is scaled down, the stamp design does not appear to be the correct proportions (19 x 22mm) for #544
I beg to differ. I checked the aspect ratio and compared it with a flat plate image and a 543 single stamp image from a plate block. The millimeter dimensions quoted above are not accurate enough to derive a useful aspect ratio. The aspect ratio from the image was about 1.17. I also created an overlay after resizing the reference image to match the width of the stamp in the image. The original image and the overlay were the same height. The image below overlays a 543 at 50% transparency over the OP image. It is also clear that a slightly taller 542 (perf 10 x 11) from the top or bottom of a sheet could potentially be reperforated at the top and bottom to resemble a 544.