I planning on building a 25'x30' addition with a crawlspace in the far Western suburbs of Chicago. This will give me about 15' walls. Since this is an addition and the location is behind my garage with limit access for concrete trucks and pumps I would like to do a 15' pour using the windows and door for getting the bottom 5' done then moving to the top of the wall. In order to do that I'll need bracing that can deal with the 15' walls. I may have access to 12', 10' and 8' bracing. An alternative is that I purchase the Zont/Zuckle system and use that, but then I need to get rid of it.
I've tried contacting some of the people trying to sell their Zont bracing equipment, but they have either moved on or sold it.
What other options do I have? Using 2x4's to make the bracing?

Yes, I would use 2x4's to extend the bracing....and have extra lumber on hand during the pour to brace and straighten as needed before it hardens up. I am not an expert....there might be better ways. You can screw 16'ers to the wall and then attach your steel bracing to that.