"I have realize a test with my fly line and a SAGE SLT 9' #4 and it's perfect but this blank is not available."
Are you sure? Ask as when I run this through Google I get several 'hits' from rod building supplier that suggest it's reasonably available here in the US. Give it a shot, and if you have a question on the supplier on this end I can easily check 'him' out and get back to you quickly.
Not to worry about buying out of the US and having it shipped to you in France. Most of these guys do a brisk business shipping to Europe, so nothing new to them.
Fred Evans
Edit: When you Google the rod blank start with 'rod building+slt.' That said, to even refine your search some more this is the link to one of the largest rod building Fora here in the US. If it's 'out there' these guys will know where to find it:
http://www.rodbuildingforum.com/index.php?act=idx
And excuse my poor manors! Welcome to the Board!!
fae