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If the existing pump is meeting your flow rate requirements, then the cheapest option is to just replace the motor with a 2-speed of a variable speed motor. If you want a whole new pump, then again a similar sized 2-speed pump would be fine. Or you can go with a similar sized VS pump. Or you can go with the full featured large VS pumps (like Intelliflo) that would allow you to run at a lower speed (quieter) for the same flow rate.
You need to consider before you start buying if you want an automation system or not. If so, then the SWG and VS pump and automation system would work best together if the same brand.
For the SWG, note we recommend sizing them for 1.5-3x the size of your pool. Given your location, I would think 2x would be fine, but given your pool size, the options are more limited to find something in the 60k size. Pentair and Circupool are a couple options.