grow room re-design help

I currently have 2 5x5x8 rooms built into a 10x5x8 room, they are seperated by a removable wall. I used one for veg and one for flower. after 2 years of using 400 watts mh for veg and hps for flower, I want to make the room bigger. Because of the space outside the room i built, Im moving my veg into a cubby hole type thing that is 4x4x5.

Anyways if i remove the wall and have a 10x5x8 room and add a 600 watt hps to the other side of the room. Can I use a 600 on one side and a 400 on the other, I would assume it would benefit all the plants, but obviously more the plants on the side of the 600.

I have had heat issues in the past, in the summer i definetly get over 85 degrees. I added a 285 cfm to take air out of the room, and since it's in the basement it pulls air from the living room there where it stays mostly cool. I vent the hot air outside a window that is hidden.

Anyways im trying to figure out how much would the temperatures drop using cool tubes to cool the lights. When everything is running properly my current temps with only the 400's works out to 80-85 in peak light time. So how much more heat would the 600 put out?

I'm not to worried about yield, I got 18 o's from the 6 plants i just harvested under a 400 obviously that's wet weight, probably 4 to 6 when dried. But this is why i've cleaned out all my rooms except 2 mothers in the new small room. Trying to find the best way to join the 2 5x5 rooms together and keeping it cool.

Thanks in advance for the help.

I think that you are doing the right thing with the room changes. You had 24W/sq foot in the old flower room and that is going to drop to 20 with this plan. That's kind of low and I am a minimalist kind of guy. The cool tubes should not only lower temps but, allow you to keep the lamps closer to the plants. How much cooler? I think that it depends on the size of the fans and the filter. Not going to vent to the outside w/out a filter are you?

I always vent to the outside with a filter. Have never had a smell issue so far.

Haha my first grow I made the mistake of venting out the window without a filter. OOps, I came home from work when lights were about to shine and the stank hit me like a fist walking up to the door. Ever been downwind of Super Skunk spunk??? I shut down early and lost the yield because of paranoia. Probably over-reacted. Now, I use a filter of course; but I also have a back-up vent into the attic in case the filter expires. Then I can just switch up the exhaust without worries.