Compatible Varios Pump with Classic 150-Int Skimmer

Hey Community, just curious is there are any varios skimmer pumps compatible with the Classic 150-Int skimmer. I really like the skimmer and it is a perfect fit for my sump, so I don't want to change the skimmer at this point in time. However, I am getting ready to change my return pump to a Varios 6 was thinking maybe upgrade the pump on the skimmer. I just wasn't sure about flow capacity of union size.

Thanks,
Chris