actually that motor needs about 23v per 1000rpm, so 25-6v for 1200rpm.... the Kv can be +/-10% so might be as high as 29v just to spin - leaves no volts to make torque.
so it iwll be pretty whimpy at 1200rpm.
volts makes speed generally, current makes torque exactly. so no matter what you do with the voltage, the current will be the required torque times the Kt constant - voltage has no effect on it - unless you dont have enugh to make the current thru the 1 ohm resistance.....
bottom line: get close to 100v to be happy. 80 prob ok. 30 and you will be unhappy I think,