In all honesty, you should probably have a max of 1 tang and 1 angel in a 75, and even then you should make sure and go with the smaller species of both. The vlamingi you already have can grow to about 2 feet and is a really poor choice for such a small tank.
Either of the angels you mentioned would be a good choice, and a better tang choice would be something a like a yellow, kole or tomini.
HTH,
Mariner