Hi, for beginning, I would stay longer than 8'. The paddling technique needed to enjoy a 8' in waves will take time (mastering the row effect, take off, paddling speed, wave placement), your windsurfing experience will not help you at first (except perhaps outgoing, to punch through the foam)
See my detailed post (in French, Google translate may help you) at
www.gong-galaxy.com/forum/viewtopic.php?f=88&t=7816&p=108613 on why you shoild avoid a 8' at first.
Longer than 9'6" is not worth it for your weight in Mediterranean (slower) waves, and you do not need too much volume. Something in the 115 - 135 liters range. Width will give you stability, but at 64kg, you can go down to 30".
I would advise a shape with wide nose and tail, for extra stability and glide.
On your selection this means: avoid the Hokua JP Pro, Manas are OK but the 9', not the 8'1". The Gerry Lopez is too narrow for a beginner (doable, but will slow the progresses)
This said, I would push you to look at other brands. I do not know where you are (France, Spain? I see you listed a shop in Labenne), but in Europe we have a lot of quality brands (better and cheaper) that are not available in Australia and are not mentioned often in this forum, but it depends on the country. The main one for instance in France is Gong (you can get a lot of useful advice on its forum
www.gongsup.com/forum/index.php (in the Gong line, the NFA 9' will be a good choice for instance) but there are a lot others, and also some quality Australian boards can be now be found in Europe, like Sunova in Portugal.