I agree there should be no problem. I have also shortened (and in one case made much longer) sync cord. The ones I have done have had two wires in the cable. Use a small piece of electrical tape to isolate the wire soldered joints. But then for a final closure, I like to use a small piece of 'shrink tube'. Remember to slip the tube onto one side of the joint before soldering. The 'shrink tube' makes a much nicer final closure then tape. Over time tape comes loose, catches, etc.