UPDATE:
My new Sicce 1.5 pump came yesterday evening and what do you know? Everything is running perfectly! I cranked the pump to its highest setting and it seems to be a perfect match for my overflow. I actually feel like we could get away with more flow, but I don't think it's necessary considering the size of my DT. I do, however, feel that I am going to need to look into some quality power heads to up the overall tank flow, so that will be my next venture.
We re-plumbed everything per all of your recommendations, so thank you all again for your feedback!
The final result is as follows:
Overflow to 1" drain hose
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Return pump to 3/4" flexible tubing to 3/4" PVC
3'-0" EShoppe 1" Drain Hose:
Sicce Synchra Silent 1.5 Multifunction Aquarium Pump:
All is working wonderfully now and I couldn't be happier!
Side Note: Now that everything is functioning as it should be, my overflow box is nearly silent. I will post a video with the sound shortly.
Thank you all again!