Besides Dave Kiff, I have also got reamers from Manson reamers.
No issue exporting as it is considered a tool/drill.
Dave Kiff is probably one of the most versant reamer guys to talk to when it comes to accuracy dimensions and wildcats. Odds are they already have it in their data base.
For you 6BR, secure your brass first. Dave will likely ask which brass you will be using. There is enough variations from Rem, Norma, and Lapua that you need to know.
In case you haven't visited, 6mmBR.com for all there is to know about this wonderful cartridge.
Jerry