Actually having the maximum recommended cable length is a good thing. It makes a natural soft starter. #10 wire will go 630' with a 1 HP motor. It doesn't hurt anything to start with #8, except that it won't give you the soft start like 630' of #10 will do.
"Reduced-voltage starters may not be required if the maximum recommended cable length is used. With maximum recommended cable length there is a 5% voltage drop in the cable at running amps, resulting in about 20% reduction in starting current and about 36% reduction in starting torque compared to having rated voltage at the motor. This may be enough reduction in starting current so that reduced-voltage starters are not required."
Heres the link;