Hidden room grow, need flowering lights

I have a few plants starting under a 200w 6400k bulb. This grow area is 4' from the bottom of the CFL reflector to the floor.

When the time comes to flower, should I run a 250w HPS in the place of the CFL, or run a 150w HPS alongside the CFL?

I'm looking to keep the wattage and heat output down. If you didn't notice this is a second-story grow and there is no insulation on the top face (yet?). If I can add any information to help please let me know.

Where is this hidden grow set up at looks like up in the roof. If it is becareful of using 250w hps. It might let off infra red hot spots up there if it is in there.
If you can vent a 250w hps whynot. I grown using a 250w hps in a cabinet. I had 3 fans, one intake one inside and one outake. It was still getting too hot inside, and nearly killed my plant twice.

Yes, that upper face is the roof. Internal ventilation is fine, the room is bigger than it looks as far as floor space goes and the current fan is quite powerful for circulation. Not pictured is a place where I could put in-fans and out-fans (small ducts rather to keep the noise down).

Would insulating the upper face keep light signatures in better? I'm not worried about running the CFL by itself during veg, nor do I think the CFL with a 100-150w HPS would be too hot. That seems to be the safe route, but would a mixed light spectrum during flowering make my buds less potent?

If you get the right mixed spectrum it will make it more potent I have grown in eavs before and didn't pay much attention to heat signals you gotta go pretty big for that to be an issue your trying to mimic the suns light as close as you can the plants evolved to live off it