Are you sure you can't use a lever and just bend it to suit so it misses the seat?
Air shift is not worth it, more complexity than necessary and you loose the feel of the shift. The trans is not synchronized so feeling the shifter as it slips in gear (or grinds) is a helpful. There were air shifted auxiliary's and even air shifted main transmissions but that aspect of them is nothing special.
If bending a lever won't work perhaps borrowing a shifter and linkage from a Chevy COE would work. I've searched for some pictures with no luck.
Grigg
