I send the wood naked. USPS has no problem with that. (I don't know if UPS would or wouldn't)
I corner round the blank with a router, write the address on the blank itself, then affix a label over that, wrap the label with clear tape, and away it goes. BBL goes in a separate tube. Don't send the tang, inletters don't inlet that for you anyway.
BBL and wood should come back as one shipment, bbl taped into the bbl channel.
Before sending:
Look your barrel over, and see if there is a flat that should be on top, or a flaw that you want hidden in the channel. Indicate the top flat with marker, protect with clear tape.
Also, drawfile the SIDE flats, even put a little taper to the flat that is buried in the stock. This makes bbl removal much easier for the life of the gun.
Ramrod channel: Mark the blank out for web thickness and at the breech. Have an idea where you will locate the front lockbolt, if using one.