You can definitely use
any non-QS (2007-2009) left shifter ...
- I found that the Xenon-based LEFT shifters (aka "QS") can handle almost any front derailleur when shifting between the chainrings of a DOUBLE crankset ... that goes for a Triple-capable Shimano LEFT shifter, too.
AFAIK, the current LEFT Ultrashift shifter (but,
not necessarily the 2011 Powershift levers) has '[COLOR= #ff0000]
7[/COLOR]' indents (vs. '
[COLOR= #ff0000]13[/COLOR]' for the older Ergo Power shifters) ...
BTW. If you need more than the G-springs, then (in the past, at least) it's often cheaper & more expedient to cannibalize another shifter (e.g., Mirage or Veloce, presuming you have Centaur or better) rather than buying all the individual parts.