The Hella turn signal switch as used on original Cobras wasn't taken from VW's as they didn't use the stalk mounted switch at the time. Later, VW Beetles came with one very similar though and modern units will work fine for a current replica. Early MGB columns are fairly common on eBay but most will need to be rebuilt with new bushings. You'll need the spacer ring to make it work and if you want to be very accurate, you'll need the column mounts as well. csxparts.com sells them.
Not a great picture but here's my column.
Larry