I didn't state myself too clearly. The active (as in glowey) deflector assembly from the TMP Connie probably shouldn't be put onto the rear of the 2ndary hull to replace the rear "sensor dish" on the TOS Dreadnought. Some imagination would need to be used for the rear sensor array, IMO.
From what you are suggesting though that the 2 small dishes on the TOS Dreadnought are the deflectors and the large dish is the main forward sensor we'd need to be imaginative at both ends.
Do you think that maybe the lit ring set back and around the outside of the TMP deflector might possibly be the forward sensor array? If so I have a mental picture of how a Dreadnought with the forward shuttle bay might look.