Ventilation For Cabinet

So what do you guys think; Im thinking about adding an addition to my cabinet to make ventilation better. Right now it stays around 80 on botton and 75 on top, but i want it to be the same. Im also concerned that i am not getting enough fresh air coming in which is the majority of the reason for this little project. I have a picture of what i have now then a shitty photoshop rendition of the final product.

In the new on, the exhaust on the bottom with the fan in it will face down and become and intake. Thinking about putting an inline fan in the ducting aswell. Do you think this is a good option?

yea man that could help a bit. Are each of those levels sealed off and light proof from the others when the door is closed? cause if so then yea that little ducting thing is good. but only if the bottom 2 levels lights are always on, and im assuming they are since they looks like clones and the veg and mother room.