i would do one ctenopoma and one hemichromis of your choosing, just not the fasciatus who will get large and mean.
one synodontis angelicus. hands down my favorite syno cat.
your african butterflyfish is the pickiest in terms of water parameters, so i would adjust your tank in accordance to his needs, which includes a tight lid. ive never been able to properly keep them. the one i had jumped the tank after about six months, but i did find out he loved live crickets to eat.
congo tetras should number 6-8.
that stock should fill your tank completely once theyre all mature. i would include some good hiding spots/caves for the ctenopoma and syno, as well as a few hanging/floating plants for the butterflyfish. i hope you do this theme. sometimes ive been tempted to chuck my red devil out the back door and set up this exact tank in his 75 lol.