Carve size question

I need help for choosing a good board - sail combination.

Weight: 67 kg (148 lbs)
Height: 187 m (74 inch)
Level: footstraps, planing, harness, I never use a centerboard

From 1986 till now I use an Alpha Fascination, freeride longboard. The board is 18.5 kg (41 lbs), 3.68m (145 inch) long, 67 cm (26 inch) wide. You can call it a dinosaur ;-) Does this make me a dinosaur too? Well, 44, so not yet ;-)

I only windsurf in south Spain (Mediterranean Sea) 5 weeks a year. The wind most of the time is 20 - 37 km/h (11 - 20 knots).

I think a Starboard Carve would be a nice replacement. But what size would be a good choice? 141, 131?
What I like: The look and shape. The footstraps positions can be placed more to the center for the first rides. I also want to be able to up-haul the sail.

What would be the best sail size for this board for winds in this range? 6.5 m2?

Thanks!

Gunther