2 plants? Man I'm not expert, haven't finished a single plant yet but that seems really tight for that space. I've seen it done I guess, but I would choose a low heat light like led or whatever, or like jcmjrt said. The last thing you want is to be one of those guys who winds up cutting off the most glorious part of the plant, the cola.
Hell even CFLs work well if used effectively. Especially in a small space like that, BC they don't put off too much heat. Do you know what strain your growing? That'll play a big factor too
Edit: hell, you might wanna consider just running one plant, topping it, and then tieing the two tops down horizontally. I'm not sure if you planned on using LST techniques or not, but it would be a good way to use up the space with a nice mature plant that might yield more than 2 single plants.
This pic is a little old, now its in flower and crowded so its hard to tell apart from the rest, but that's exactly what I did to this one.
Just food for thought. I'm always trying to improve my yield in any case possible, there might be other really good ways to increase yield in a small cab like that
