So Island Recreational said it wasn't worth it to oversize the heat pump too much, their recommendations were:
32,000 BTU - 5,000 gallons
53,000 BTU - 13,000 gallons - 25amp
65,000 BTU - 15,000 gallons - 32amp
80,000 BTU - 20,000 gallons - 40amp
I have 8,500 gallons, so I went with the...