I'll go ahead and trust you re: darkening, Biker.
But... I'm not sure I get the thing about dimensions. They are all power of two, and I'm positive I've seen rectangular textures already in the dark mod.
Keep in mind that google's galleries auto-resize stuff for viewing, but downloading should yield the intended sizes.
Edited by Bob Necro, 09 July 2015 - 03:03 AM.