Make your Cougar run faster, handle better, and jump higher... okay maybe not jump higher. If you feel the need for speed, this is the place.
It really depends on you personally and the price tag. I personally don't care about it being numbers matching, however I didn't pay for a numbers matching car and plan on modifying some things anyways. For a low production vehicle it would mean more. It's 50 years old and was sold as a performance car so there's a good chance someone had to throw a new motor in.