Well, there is 
the original image.  To restore it you would need to burn it instead of new_opt.900.img.  You may want to unpack it, re-pack it again (so it isn't as big) and generate the MD5 checksum (new_opt.900.md5).  
The latest Russified images (
1.05a) allow setting the timezone to pretty much any offset (via the special config interface in the About Reader screen).