Quoted from rufessor:Good eye- thats actually the NOS target I acquired to replace one that was broken or missing when I got the game (I dont rember which!). Funny its actually a little more yellowed than originals in game. But close enough. I may try the peroxide trick to de yellow but maybe not. It looks ok and I only have one more NOS target and I doubt any more exist....
In all actuality I was poking fun at the explicit level of detail you have gone to with this game. As I stated before, you should feel good about this effort.
I would not get worked up over trying to lighten that target. Any fluid you apply has the potential to damage or remove the art. The art images are fragile on the original drop targets.
What I would do is look for a clean original target if you really need to address it. Hard to say why the NOS you found is yellowed more than the originals.