DGR's translation of the original sonnet is exceedingly free, even in the deployment of its rhymes. But the result is so successful as poetry, particularly the exquisite sestet, that one can hardly find fault with the liberties he took.
The source text is
Poeti
del Primo Secolo
As with most of DGR's translations of the early Italian poets, the date of this cannot be precisely determined. It is probably an early translation.
The translation was first published in 1861 in
The
Early Italian Poets
Dante
and his Circle
Early Italian Poets
Poeti del primo secolo
Le rime della scuola siciliana