Will that be enough for 2ft x 3ft space (HLG-240H-C1400 can run 4) or do I need to do something else?
A 2 x 3 space is 6 cubic feet. You would want a minimum of 35 watts a square foot with Cobs that are efficient as the gen 7 veros . Personally I would go with a HLG-240h- C1050 and 6 of those veros. That would be 40watts a square foot and you can center a cob in the center of each of your 6 square feet for better coverage. Adding anymore watts per a square foot you would have to run Co2 to utilize the extra light. So if you went with a HGl-320h-c1400 and 6 veros 29's you would need to add Co2 to use the extra light as that would be 50 watts per a square foot. So it really is kinda up to what your plans for growing are if you never plan on adding Co2 i would go 40 watts a square foot and if you plan on adding Co2 go 50watts a square foot.
I was thinking about this exact same setup with 320h1400 in a 20"x46" area which is about 6.4 sq ft. I'm not sure about C02 yet, but wouldn't I be fine just raising the lights or dimming the driver if it seems like too much? This fixture will be strictly for flowering.
I would listen to this guy. I was stubborn and didn't listen and bought the hlg 2.1A driver for my Vero 29 L-23's. You could literally cook a steak on the pins of my 140mmx80mm heatsinks. I picked up a HLG-185H-C1050 and now I run 5 chips at around 40w for 200w total. Bright as hell, no heat and I can keep them 8" from the canopy.