put a hummer front shaft axle shaft in (makes it a solid shaft, no shift fork or collar needed) or buy one of the upgraded ones from dhd or another place
As for shift linkage, just grab a floor shifter from any gm truck/suv in your body year range. You may not use the full linkage but the shifter will bolt in easier and carries the pivot and just may have to do some modding time the linkage side.
Keep in mind I have the 1/2 ton diff. Not sure the Hummer shaft for the 9.25 is the same.
As to the lever, it looks to be a flat piece of steel bolted to the shift shaft with a linkage ball on the end. I dont see an issue cutting a square hole on one end of a piece of steel and drilling/tapping the shaft for a retaining bolt. Thank you for the idea James.