We have a Hayward NorthStar single speed pump (SP4000, MOTOR IS SP1607-Z-1-MNS), 1 HP; this is the original pump (20 years old +) and I want to replace with a new VS Pump, I am trying to decided which one will be best for our pool, in-ground, approximately 35,000 to 37,000 Gallons, has a Hayward  DE6020 Pro-grid filter, 1 1/2" plumbing. What is the best recommendation for a new pump?