What are your plans for the Mustang once the Camaro arrives?
If your plans include selling the Mustang in order to get the Camaro, I think that answers the question.
Personally, I would save, save, save. As Tag stated, I too want to do a few more things to the SS, but I'm saving for the new Camaro.
Your Mustang is a really nice ride as it is. Enjoy it as is, and save your money.