Well, in all technicality, every weapon in Aces High has a "sight" at the very center of the screen if the head position hasn't been moved in the x/y directions. However, rangefinding is the issue.
I've read that the main gun couldn't fire while the Calliope was mounted and that it was aimed using the same sight as the main gun barrel. I doubt they would model it any other way than to be able to launch the rockets from the main gun sight. However, whether that will be a simple red cross (ala the Firefly's smoke rounds), a metered sight (ala standard tank main gun), or a full readout (ala ship guns) remains to be seen.