Yes but ....
If you are using the standard TO-220 uninsulated package, the bare metal back is connected to the Com terminal. Which means if you are using a heatsink, it will be at + 300 VDC with respect to the bottom of your diode string. Since you are dropping approximately 16 Volts across the regulator, a heatsink will be most likely required.
IMHO, it is not most reliable design to operate the regulator up against it highest voltage limit. I personally would use a zenier diode string and dropping resistor to get the voltage to 330V and then use your circuit with a LM7806 to regulate it to 324 Volts. That will give you a little more protection against high voltage input.
Larry C
