What calibration options should I look into given these defects
Your print does not suffer from layer shifts as you call them. This uneven layer deposition is typically caused by the (positioning) accuracy of your printer. All-in-all, this print does not look so bad. You would get better quality prints on a different style of a printer; most high-end printers have a lowering platform instead  of a forth and back moving platform.

Although 180&nbsp;&deg;C is at the low side of printing PLA (usually it starts at about 185&nbsp;&deg;C), the print does look okay. However, looks can deceive, it does not say anything about structural integrity (layer bonding).

Note, to calibrate the temperature using a temperature tower, you need a different calibration test print, preferably one that tests overhang. This latter is usually far more important as there is normally not much to see at the walls, you need a slanting part in the print or an overhang to determine the optimal temperature.