Guys I check with surftech website what size they would suggest for me and the result is a 6'8"x 19+ x 2" 5/8. That was a board around 45cc of volume. Yes I know that I have to loose weight, I'm about to start working on that.
I know that this is actually a litle big board but this size if for pure surfing
Let's say that I can have a board shapped for me, should I ask for a board of such a size or I could shape out a smaller one (6'2" - 6'5" x 18" 1/4 - 18" 3/4 x 2" 1/2 - 3") but approximately the same volume. In this way I believe I won't loose the performance that a smaller board would have and I would still have the volume to keep the kite power to board buoyancy ration the same.

The goal for me is to have the same board I would use for pure surfing to kitesurfing in a way of speaking.

thank you for your time guys...

Spilll the beans.
Hard to have specific advice without:
Your weight
Your skill
Your surf conditions
your kiting conditions.
But generally:
If you are a good surfer and like tiny boards, 6' or less, get one and it will be ok powered up kiting.
More length is ok for kiting usually, but too much width can make a bumpy ride.
I am 80kg/176lbs and have a 6' x 20" board, I kind of wish it were 6'4" x 18, for example, because I end up riding in choppy water often.

It sort of sounds like you want a fish? A fish over 6' will float a big dude, if you're big.
Not sure though.... ?