do you know where i could buy any of those preferably in the 4-6 inch range???Don't get a haitensis or buttikoferi- both will need larger tanks than an 75. For a 75 you want to stick with a fish that reaches a maximum size of 12", preferably a little bit smaller. Some realistic suggestions of fish that will still "glass bang" and fit in a 75 are:
Istlanum
Tetracanthus (Cuban)
Amphilophus Lyonsi
Green Terror
Female Midas/red devil (males get a bit large for 75)