Including extra back work will improve all 3 lifts.
Even though I don't squat I still do good mornings and with the extra back training added in about 3 years ago the weight on my back feels strong.
- goodmornings 145x8x8
- reverse hypers 4x15
- deadlifts 275x5x5
- chest supported row 4x10
- power shrugs 3x20
- pulls ups 2 sets till failure