I use the American Auto Wire toggle turn switch. I made a small angle bracket that mounts under the dash of my '40 using stock under dash holes to mount it. Added two small green indicator lights and it's good to go. I use the front parking lights and the rear brake lights for signals. It's a simple system to wire into your existing harness. Got the switch with terminals and instructions off e-Bay for $25.
The other option if you still want to have a switch on the column is using the VW bus switch. The only drawback is the mounting bracket will not allow you to use the switch on a car with a column shift. I have one of these on my '41 pickup and if you paint the switch body column color it almost looks like something that was stock. These switches are hard to find used and new ones are about $100.