Agreed, but not for a 75g. IMO a mix of senegals, delhezi and palmas variants would be nice. I hope you're not buying the tank and the fish at the same time though, although polys are generally tough I wouldn't want to use them to cycle a tank...
Dude, your buying your 9yr old brother a 75g tank and birchir for his birthday.............someone should nominate you for the most badass older brother award.
Good stuff man.