You're done the great job!
But it can be improved some further. So use PINGA (css-ig.net) app so you can compress this textures more up to the theoretical limit (up to minus 36mb more from this Space Age Base files) without losing quality (images must be at 256 colours already from last compression, because 32bit images are so huge in size, you know)
Best regards.

Thanks for the tip, I'll have a look. I have more important things on my to-do list at the moment. One thing after the other.

Thanks again for the tip with PINGA, I have now compressed almost all mods with it.