U might b a little off on ur lumens. 2x42watt is about 2,800 per, so 5,600 lumens and 2x23 is about 1,425 per, so about 2,850 there. So roughly 8,400 lumens.
With such little lights, ventilation should b extremely easy. Just drilling a fewholes in the bottom of ur box and habit the CPU fans at...