I am not aware of too many major gunsimiths or custom builders that will put you toghether a complete custom gun. The only way I could think of is if you were to get some sort of lisence and take it to a gunsith in the US, like Bill Calfee, or someone like that.
But if you find a good shooting anshcutz, Valmet, walther, ect, not a lot of custom work will need to be done to it, besides bedding it and a bit of accurizing, but nothing you or the local gunsmith couldn;t do.