Is the 490' to the top of the well head or to the pump? How deep is the well?
What is the AMP rating of the 1HP pump, I am assuming 240V?
Personaly For 490' and a 1HP pump I would be using a #10 minimum and most likely I would run #8 to a locking, water proof box with a GFCI receptical in the box near the well head and feed the pump from it. Voltage drop is what you don't want.