Contact Michel Martel, at Armurier Lavaltrie. He made some for me in the past. There's almost no limits on what you can get, it will depend on $$$ you want to spend. Don't expect to have it back the day after though.
So today I brought the rifle at Armurerie Lavaltrie.
Michel seem to be a gr8 guy to work with.
It should be done in less than a month
Finally I went with the custom picatinny rail.
It's like Christmas approaching