Here's an idea: The German Assault 13 have the best colors, but not the best compression. Since it uses the exact same master as the recent edition, perhaps you should apply the colors to a better encoded master.
+ the german dub have about 20mn of additional music in the film. How about recutting that music in the US soundtrack?
+ put in there the LD soundtrack music (and use it for conforming the german audio music to the US soundtrack) and LD sound.