Seems that like most supplies lately, I am on an epic quest. The Grundfos pump is not available anywhere. There appears to be an AY McDonald stainless available. The impeller is a type of plastic. Given the downward spiral of our supply chain I think I should just grab it and be glad.
David,
Get as big as a pressure tank that will fit, 8 or 10 gallon drawdown and stack the tank in the corner as mentioned above the water softener - and use the CSV - get the best of both worlds - constant pressure when needed, less cycles and not turning on every time you brush your teeth or wash your hands - it's really simple - you want to reduce the starts/stops on the pump.
For the pump, getting a large 1HP pump - 15 GPM is actually a bad idea, it will draw more amps starting and running and be overkill for your house. A Goulds, Grundfos, or AY McDonald 3/4 HP 10 GPM model will produce 12 + GPM at your water depth and with your in flow or recovery rate of (20 GPM) , and a 7 GPM rated pump will deliver 8-10 GPM at your depth and in flow rate to the well.
Personally, I have a Goulds 10GS15 (10 GPM, 1.5HP) for 20 years, set at 365' and it pumps 14 GPM at 50 PSI most of the year, and when the well is low - dry times produces 10-11 GPM, and I wish I put in a 7 GPM 1.5 HP as it would better match our max usage (8-10 GPM) with less cycling.
The key to a long lasting water system is to size the pump and system to your usage and minimize the number of starts/stop cycles over the years, and that is best done with a "right sized pump and storage tank" and a CSV which will minimize the starts/stops and not turn on every time you draw a small amount of water.
You can do what you want, but don't over size the system - 1" pipe, 3/4 HP 7-10 GPM (will produce 8-12 GPM), a 8 gal drawdown tank would be ideal.