Barrel question first

There are numerous American Gunbuilders who can make your barrel. The regulations around exporting a gun barrel out of the continental USA are tedious to the point of being prohibitive.

One such Gunbuilder who comes to mind is Duane Wiebe of Tacoma Washington.

I won't bother to estimate a price for you, besides noting that the job is expensive.

Chassis stock question

HS Precision, McMillan, and some others offer composite stocks featuring integral metal bedding block systems.
I do not know of an American stockmaker who is offering hardwood stocks featuring this type of bedding system - but there may be someone doing it here in the USA

Cheers