Yes, you'd probably get the credits music if you use DOSBox + original CDs.

ScummVM does have this music however, and I imagine this is the reason GOG decided to use ScummVM instead of DOSBox.

As I said though, DOSBox +GOG's version does have all the other music, so if you want you can just use ScummVM to listen to the intro, and then use my method to play using DOSBox.