Trying to print actual size

[lsemmens]

I have a design for a pickguard for my bass guitar. I've set the sizes according to the measurements on the instrument and, according to gimp the print  size is 232.49 x 274.49 mm. A standard A4 page is 210 x 297 mm. If I opt to print, or, print preview for some reason the image is scaled down to 210 x 297 I cannot find a method whereby Gimp will print Actual size. Obviously this would entail two pages, which is my desire.

How can I convince Gimp to print this image correctly?