COB LEDs array in parallel driving circuit
You have good idea but values are way off.
With 120 Ohm resistors you would need 72V supply to get 36v@300mA across LED's, and you would waste 50% of energy on heat.
Reduce resistors to 6-12 Ohms 1W, and get power supply that can be adjusted to 39V(most aliexpress cheap ones are adjustable +-10%).
Brightness differences,if any, will be unnoticeable.
PWM dimming will work.