bake pushrod length question

[donthekawguy]

I put the captainfab bracket and booster on today. What is the best way to get the correct length for the pushrod? I'll have to take the booster off to get a threaded tube for the booster end but from there I'm lost. I think I read that I have to drill a hole an inch lower in the pedal arm and cut threads in the old pushrod but I have no idea how long the rod needs to be. Do I just cut enough threads into the old arm and adjust it as I go?