Once you determined the voltage of the Brake coil, you then select your rectifier depending on your supply voltage, you may need to use full wave or half wave depending on the above two factors.Usually the Brake manufacturer supplies the correct rectifier with the Brake, so you don't run into problems like arcing on the contacts.

Your posted values lead to requirement of 600 V @ 0.75 A. Only getting a suitable rectifier does not suffice. To get 600 V DC you will need more than 400 V AC, requiring a step up transformer suitable for your utility supply voltage. There is more to it than you perceive. For you, the misery of designing a suitable unit, does not end so easily.

When you have a single side rectifier the output DC voltage is +/- 45% from input voltage. If input voltage is 400 Vac, output voltage will be 180Vdc.

When you have a double side rectifer, the output DC voltage is +/- 90% from input ac voltage. If input voltage is 230Vac, output voltage will be 207Vdc

Most rectifiers also have a voltage dependent resistor to surpress the voltage up-swing at the moment of disconnecting.

Most rectifiers also incorporate 2 connection points to interrupt the current at de DC side. (between rectifier and brake coil). If you interrupt de DC side, the motor will not work as generator and the magnetic energie removal from the brake coil will be faster. The result is a shorter brake time.