Watchman Goby-Great
Pistol Shrimp-Great (not sure if Marine Betta will eat it though)
Ocellaris Clowns (2)-Must have for any tank, really. Great. If I were you I would get either the original or the Black and White variety, no designer clowns for me but it’s your tank.
Marine Betta-Great. And a must have fish for me.
Flame Angel-Great.
Snowflake Eel-I know very little about eels, from what I’ve read they don’t need that big of a tank, but they are very much a predatory species that exert a very large bioload. I don’t know about them as I don’t plan to keep one myself but I’d be worried about your smaller fish. They also need a VERY tight fitting lid as they may try to escape like a snake. As for the Snowflake Eel itself, consensus has it that it’s probably the easiest eel to keep but it does look a tad bit.... specialized to me.
Kole Tang-It’s one of the smallest tangs but tangs are a very active fish and this one still gets to 7” I think. I don’t know if a Tang can be happy and healthy in a tank of this size, so maybe Tang keepers should answer this instead.
TBH if I were you, I would do:
x1 Marine Betta
x1 Flame Angel
x1 Watchman Goby + Pistol Shrimp (Yellow Watchman or a similar species in the same genus)
x3 Pajama Cardinals
x1 Yellow Coris or one of the smaller Halichoeres wrasses (LA lists them as ‘Reef Safe With Caution’ but I haven’t heard anyone having trouble with them in a reef)
x1 Royal Gramma or a similar basslet
Maybe a couple of Chromis or Chrysiptera genus damsels (Talbot’s, Azures, Springer’s, Rolland’s)
Feel free to critique my stocking plan for OP.