I have taken a quick look at a sample of these stamps. Here are the images. All are with the 12 mm, or wider overprint, with the exception of the 1L, which has the 11 mm, or narrower overprint.
1E2, thin, very porous, white.
1E3, white to cream, medium thickness.
1E4, white, thin, porous.
1L1, looks a lot like 1E3, used for the 11 mm overprints of the 1950s
Here is a comparison on the 1E3 with the 1L1
I also find a few with the A in the watermark partially missing the legs. Stamp is 1E3.
The unwatermarked grid, NGR, is the top two rows of the scan below, and the unwatermarked opaque NOP, is the bottom two rows.
Here is a comparison scan. The NGR is grayish, and the NOP is white, but this deifference is not obvious in the scan.
With higher contrast ('equalize' in Photoshop')
I hope you find use for these reference scans.