Also, congrats on the transformation!
Based on the above Post, you will likely want to add venting in the top near the front . I would look at Audio furnace as a parts source. They also use (box) fan(s) to bring air in with placement along the back panel near the bottom. A screen cover on the vents ports is a very good idea. If you have an Audio store in your area (thank-you for including a location) they are generally a good source or can recommend a source. Just tell them its for your Audio system, it will save you lots of time not having to explain what the heck you are doing.
Look at replacing the lights with full Spectrum LED. In addition to being very cool (low heat) they will cause your Bird's colours to really POP!
FYI: You may want to consider using a 'water based' sealer on the interior of the case. As a gun case, any sealer would be fine, with birds, may need to upgrade the sealer. It will likely extend your start date a few weeks to allow for full drying, but in the long run, it will be worth the extra effort now.