You may want to lend some consideration to aftermarket barrels from sources like Aber, Lion Marc, RB, and Armorscale. Each manufacturer offers the MG 34 barrels in machined brass and it's truly as simple as drilling a hole and gluing the replacement barrel into place. Best of all, each offers the armored jacket which distinguishes the MG34 on the Tiger from its cousin slogging along with the infantry.
The link below takes you to a page with a photo of the Aber offering. The page says that it's been sold out for a while, but a quick search of e-Bay shows a lot of these barrels out in circulation. Google the other manufacturers and see what strikes your fancy!
http://www.1999.co.jp/eng/10245020