I need to replace my pool pump as the bearing are gone and I am leary
of previous cavitation trouble. I have been to three different pool
stores and have been given three different recommendations. Now I want
the real answer, not just what they are trying to sell me.

Specs:

20,000 gal pool
Pool/Spa combo with 4 spa jets
2" PVC supply lines
2" PVC return lines
Pump - currently a Pentair Whisperflo 1HP Full-rated 115/208-230 volt
(original equip from 1986)
Filter - Jandy CL460 Cartridge
Heater - Raypak RP2100 Natural Gas
Cleaner - Suction side Kreepy Krauler type
Equipment is located about 40 feet from the skimmer
Need to have a pump that is as quiet as possible as it is located right
under a window of our house.

Advice so far:

1. Replace only pump MOTOR and seal with same exact single speed 1 HP
Whisperflo motor. (Was told least expensive and all that needed to be
done)

2. Replace entire pump with single speed 3/4 HP Full-rated Pentair
Whisperflo.
(Was told the larger pump size causes cavitation and is louder, and
that 3/4 is plenty strong enough for spa jets)

3. Replace entire pump with 1.5 HP Full-rated Pentair Whisperflo.
(Was told needed larger pump to match large filter size and decrease
circulation time)

4. Replace entire pump with 1 HP dual speed Pentair Whisperflo.
(Was told it is the quietest ,most energy efficient, but more likely to
malfunction early and much more expensive)

Questions:

1. Is filter oversized? It is brand new, put in by the pool company
that replastered.
2. Which option above is best for this pool? Or other option even
better?

Thanks!

Wes