I use www.adamone.com for finding a prop that can run on 2 or 3 cells with the same engine & prop. It really simplifies the prop selection without buying needles props. the C O G balance point does not vary that much. I test install ALL parts in their locations with 2 cells. then check it with 3 cells. I put alingment marks on the batteries & the plane so it always balances fine..........Remember the 3 cell is the SHORT WIDE OPEN THROTTLE run setup & you will be fine. It is also my VERY windy day setup.
2 cells are for calm sitting in a chair flying.

Select your prop on a calculator. It will also give you the amount of W O T time as a guide.
Remember. The prop determines the motor. OR the motor determines the prop. batteries & ESCS follow the motor & prop in importance.