Os seus olhos eram portugueses; isto é, reflexo perenne dos intimos pensamentos; tempestuosos com as procellas do coração, sereno com a calma delle. No rosto do mancebo estava escripto o nome da sua terra natal: era um filho das Hespanhas: a cor, o gesto, o olhar, tudo dizia que ahi dentro havia o espirito de um godo e ao mesmo tempo que nessas veias corria o sangue de um arabe.
Hi, EY; sorry I only saw this today. I don't know if you might be interested in a more literal translation, just for the sake of confirmation:
His eyes were Portuguese; that is, an everlasting reflection of intimate thoughts; tempestuous with the storms of the heart, serene with its calm. On the face of the youth was written the name of his native land: he was a son of Hispania: color, gesture, glance, all told that here within was the spirit of a Goth, and at the same time, that in these veins ran the blood of an Arab.
So the translation you have seems okay to me too, except for the possibly German comma in 'indicated that.'
As Carioca says, the original spelling is old-fashioned and the diction is literary. In case you had any need to check individual words in a dictionary, I believe modern spelling would be perene, procelas, dele, escrito, aí, and written accents on íntimos, espírito, and árabe.