Randy,
One of the things I had to do on mine (and the other 3-4 shifters I've worked on) is maximize the throws of each lever in the shifter. There are heim joints in the shifter and I extended them or retracted them as far as possible to get the max movement at the cable connections. If you haven't done this yet, I'd recommend you start with that.
For at least one shifter, I replaced the male heim with a longer one to get even more travel. Not sure you'll be able to double what you have (19 to 35mm) but you should be able to improve the total throw available.
Chris