I constantly hear that retail sharks are aggressive so I'm not so sure that your situation wasn't just luck that is making it work, no offense. But it does intrigue me and give me thought for future stockings....
I don't think the livebears would work, the Senegal bichir would definitely eat a good many and the angel fish may decide he once to try sushi. He has been with tetras and even guppies, but never fry. If he does, then I'm sure those 2 could wipe out all guppies within half of the time I gave them to establish themselves. If I gave them 6 months to breed, they all would be gone within 3 :/. Besides, I'm planning a tank for raising live food