"Has any one though of putting them in a 7.3?"
Thought about? Yes.
Done it? No...
Aside from issues/opinions about downgrading to 6.0 injectors, the 6.0 injectors don't operate like the 7.3, so the computer would need to be changed. Not to mention a lot of other work to even make them fit, oil & fuel supply, etc, so in the end, it simply isn't worth it...