For those who have retrofitted and installed a standing column system with your existing well, what did you find needed replacement or upgrading of the existing systems (well pump, pressure tank, supply lines, or other items). I have the needed depth and yield with my 400 ft well; but which has a 3/4 hp pump, 36 gallon pressure tank, and 1.25 OD poly supply pipe. I have a company to trench to the well to install the discharge pipe in a new pitless adapter (and bleed-off line to existing underground driveway drain pipe). The heat pump units (2 tons and 2.5 ton) will replace the 2 gas furnaces and outdoor AC units. I understand a variable speed electronically controlled pump and 100-gallon pressure tank would be better, but what I'm looking for is what's nice to have replaced vs. what's absolutely needed. Pumps and pressure tanks usually have finite lives anyway and I'd rather they live them out first before replacing. Then of course other items you can think of that needed replacement.