In the song Kelly the Boy from Killane, the lines "Seven feet was his height/ with some inches to spare" are accurate. John Kelly, the son of a prosperous farmer, was well over seven feet tall, and apparently a fine-looking man.

When the Rising in which he'd taken part failed, and its members were being pursued and hanged from the nearest trees by the English yeomanry, Kelly was too tall to hang from a tree, so they hanged him from a bridge instead, then played football with his head around the main square of... was it Enniscorthy? Wherever it was, his sister lived on a house abutting the square, and she looked out the curtains to see this grisly game of football with her brother's head.

As far as I remember, the story is somewhere in Jonah Barrington, but you'd have to go through it chapter by chapter to find it.