I wouldn't use it as a fn because it is hopelessly old-fashioned. Also I always have to the think of the line "
Heinrich mir graut vor dir" (=
Heinrich, I'm afraid of you) from Goethe's play "
Faust". But I guess this association isn't a problem if you don't live in a
German speaking country.
If you want to use it to honour your great grandfather, I'd use it as a mn.