Mmmm.... I’m not the best person to ask but I’m inclined to say yes, you are veering towards the overly ambitious side.
Emperor gets over a foot long.
Asfur gets to over a foot long. Tank’s too small.
Regal could work, just make sure you can find a very good specimen because it’s a hard fish to keep.
4 Flame Angels as in two mated pairs? I’m not sure if that would work, but maybe if they’re two mated pairs you stand a chance. IMO I’d keep it at a pair or at most, a harem (1 male 2 females).
@OrionN would be the best person to ask.
Yellow Tangs are a good choice. Not sure how having more than one works but feel free to ask.
Moorish Idols are best left in the ocean. If you really want that look, get a Heniochus spp. bannerfish instead.
The butterflies I am not sure how mixing them works, but I suppose you could try mixing 3 different genuses.
Instead of the very large angels like the Asfur and Emperor (sorry to burst your bubble here), you could consider angels of the Genicanthus spp. They’re quite reef safe, I’ve heard mostly good reviews of their hardiness, and you can keep a pair or a harem (1 male 2 females) in your tank. You could even mix species if I’m not wrong. Watanabe, Spotbreast, Japanese Swallowtail, Bellus, Lamarck’s are the ones available. Sometimes the Red Sea Swallowtail. Lamarck’s is the largest out of these so if you get a Lamarck’s you could keep a single one and do a pair of one of the smaller species (Bellus, Watanabei, Spotbreast) or keep a pair of Lamarck’s (if you can find a male one) and a female of a smaller species.
Some angels of the genus Chaetodontoplus and Apolemichthys could also work. If you want to go easy, something like A. Xanthurus or A. Xanthosis would work. The latter is rarer because it’s from the Red Sea. Easy angels though not the most brightly colored. Among the Chaetodontoplus angels the largest you could fit would probably be a Scribbled.
The Copperband is also a difficult fish.
In terms of bioload, it would serve you better to ask the more experienced members. I’m just giving my 0.02.
Do you intend for your tank to focus solely on angels and butterflies?
P.S. If you have the luck AND the money, you could look into a Clarion Angelfish. It’s a Holacanthus but it’s the smallest among them, topping out at 8”. Try to get a captive bred one if you can. The reason why these fish are so rare is because they’re collected in a very limited range along the Mexican / Central American coast and in protected waters. Reportedly very hardy, but make sure you have everything planned out before adding one because if anything goes wrong, that’s 3000+ dollars out the window.
If you want a very expensive dwarf angel (Centropyge) that’s not C. narcosis or C. pylei, you could look into C. joculator (only collected from Cocos-Keeling) or C. interruptus.
But if I were you I’d play it safe lol.
