I know Grouperhead has a 75 gallon tank with a snowflake eel, lurane wrasse, and a humu trigger. Some other fish that'll fit in a 75 gal include: small lions (dwarfs, raditata, antennata), medium sized wrasse (lurane, harlequin tusk), small triggers (niger, humu humu, pinktail, blue throat) and most eels (snowflake, chainlink, golden tail) I could see 3 of those fish working together. Also what type of filter system will you run?
-Mark