Aaron,
That boss was designed for Suntour top mount down tube shifters. The
shifters attach to a single unit which then bolts to the boss. I have
a bike with these shifters and the rear shifter actually "auto trims"
the front shifter when moved. It's gimmicky and unnecessary but kinda
cool. You have a few options:
- Obviously, you can keep an eye on eBay for the top mount shifters.
Here is an example:
http://tinyurl.com/ygjazg
- You can buy a clamp-on downtube cable stop and install it above or
below the existing boss. I've bought several of these, NOS, from this
seller on eBay:
http://tinyurl.com/y6mtbb
They work very well and are pretty slick looking.
- Lastly, for a cleaner look, you could hack saw the boss down and
install the clamp-on stop over the previous boss. Some may cringe at
such a suggestion but I do this kind of thing all the time.

Best,
Derek