I am new to the forum and looking to add some birds to my home. I have two double critter nation cages that I want to re-purpose (if possible). I am planning on housing budgies in one cage and finches in the other, but am unsure if the dimensions of a DCN are suitable to finches and know that the wide-opening doors may pose an issue.
Each half of the DCN is appx. 36" long x 24" wide x 24" high. The bar spacing is 1/2". Each half can be used separately, but I have also seen some bird keepers remove the middle floor and turn it into one large 48" tall x 24" deep x 36" long cage. The shelves in each level can be removed (as well as their supports).
I have three main questions about re-purposing these cages, for finches, and would like to get your thoughts on them.
1. Would the width of these cages (36") allow enough flying space for finches, and if so, how many would comfortably fit?
2. Would using the entire cage (48" tall) be beneficial to finches, or do they tend to not use more vertical space?
3. The doors are half-width, so when I open them to add food / water or change the bedding, that means a 2' tall x 1.5' opening for birds to fly out of. The cage will be in a secure room, so escapees could be caught, but do you think this would pose a major problem with daily maintenance?
I will attempt to attach a couple photos of the cage below. This is with it setup for my rat mischief.
Whole cage closed doors.

Top half of cage with open doors

Please let me know your thoughts. If these cages will not work for finches, I can always purchase a cage for the finches and sell one of the DCNs if need be.
Thank you for your time and help!