The minimum height of a tank for angels should be 18” tall. My 40B is roughly 19-20” tall and I never had an issue. I’ve had angels for a little over 10 years, my oldest was 8 years old. My blue marble is 2 years old and roughly 5-6” tall and my koi is 4” tall and 8 months old.I have not read the entire thread but i have a few comments on the stocking. I would drop the angel - at least my angles would not want to be in my 40B - just barely enough vertical room for a mature angel. Also i would not put gold zebra in there - dwarf loaches are fun fishes and a fraction the size of gold zebra.... It isn't just the length but the bulk - also they love to jump....
Ok I skimmed the thread you replaced the gold zebra with kuhli - good choice.
I’m doing a major over haul on the tank but the other fish that are staying is the blue angel, all my barbs, loaches, stunted featherfin, and bettas. I’mtaking the koi angel, gold kribensis, and platys to a lfs for store credit and maybe get some plants and a bristlenose pleco.