does your tent have to be in a closet or anything, or can it just be in the room? If so, and your room is generally about as cool as you say it is, we're pretty much in an identical situation, except im in tent ina closet, so my temps maaaay be a few above yours but your set up even better than I. I would find something like the Vivosun 6" 390cfm fan, or something similar, on amazon. get that, some 6" ducting, and if you need it (I've never found it necessary until mid flower, but others may need it sooner) get a 6'' carbon filter. some 6" ring clamps to hold it all together. Should work out just dandy. I run my fan on the lowest setting and it pulls really well. That fan or a similair one will be good for the 600, and probably so even if you upgrade. Then hang your light, your fan, and vent the two together out of the tent in as straight of a path as you can. each kink and bend will add a bit more resistance.