Hm, still telling me the file is too big and that the maximum allowed size is 512KB. Is this an image-only thing?
Anyway, here's a shot at ISO1000, 1/100s exposure. No luma noise reduction, so it's very noisy. This shows that the text is still a bit soft at 1/100s exposure, so at least some of the softness is probably from the lens; it's certainly softer than what I get from my sharpest lenses focused properly. However, the text still seems quite legible and would respond well to sharpening at base ISO.