Kathy,
First of all, nice score on the Memphis Slim.
I have the Memphis Slim on my Speedmaster. I just took some pictures to show you my setup. They aren't the best picture I've ever taken, but you'll get the idea. Read on below:
The top picture shows that the turn signal sits far enough behind the wind screen that they should not interfer with eachother. I 'think' that would be true with the TBA handlebars also. The second picture shows the position of the light behind the screen. Notice that I use a 2 inch tab coming off the mounting post to offset the lights. That isn't stock. The tabs came with my Triumph Summer Screen, and I left them on the bike when I changed to the Memphis Slim. So the only problem you might have is the the shield will partially block a direct front-on view of the turn signal. It shouldn't be a problem if your wind screen is clear.
I'd say just mount it up and work from there.
Hope this helps.
John
PS, that black thing tied to my handlebar is a small case for sunglasses. If someone would make an attractive, well made leather case that hold 2 or 3 pair of glasses and fits on a speedmaster handlebar, I would buy one immediately.
