It really helps to have a numbered drill index for rigging RC model controls. HF sometimes has them for about $10. The other item is a $20 dial caliper or digital caliper to take accurate measurements of all this tiny stuff we play with.
I sometimes sharpen the end of whatever size pushrod I want to use, then heat it with a propane torch just hot enough to push it through an existing servo arm hole. This has worked for me. I also use a drop of oil after the "Z" bent wire has been installed to prevent the junction between the wire and the servo arm from wearing out.