Constant Current Source for the control of 960 Leds

[firstoption]

Good day to all,
Please i need your guide and support in the design of a Constant current source for the control of 960 Low power Leds Brightnes using PWM Signal.I have 8 pieces of PCB boards with each board having 120 Leds on it.The Leds are arranged in Parallel and Series.So each board has 24 Clusters x 5(a Cluster is made up of 5 leds in parallel)which is equal to 120 leds.Each of the Cluster is connected to another Cluster in series.
The Led operating voltage is 3.2V @ 20mA.From this information i calculated the required voltage for each board to be 76.8V7/100mA.After going through the Internet i came across this Led Controller(LT3756) from linear Technology which has an Input volatage range from (6V-100V)DC and an Output voltage up to 100vdc with current-source Regulation.My assumption is that this Led Controller(LT3756)will be suitable for my design.But i have two question concerning the use of the LT3756.
1--Do i need to use 8 pieces of LT3756(one for each board) for the design OR one Piece of LT3756 will be enough since i want to use a constant-current source to drive the leds.
2--I have a power supply which i made use of in my last design,this power supply has an Input range of (3.3V to 32V)dc and an Output volatage range up to 30Vdc with constant Output current of 6Amp.Will this power supply be enough to power the LT3756 led Controller which will then drive and control the led brightness using the PWM Signal it(LT3756) generates.
I would be very grateful if somebody could put me though with respect to this design.thank you for the usual suppot.best regards.
Firstoption.