Z-bar questions with big block

Thought I had my Z-bar fabbed to work but after I assembled everything along with my Schumacher headers it looks like I won't have enough travel before hitting the header collector #-o
So a few questions are; how much travel do you need, does it matter where the travel is and does it matter where the top of the Z-bar is according to the firewall?? I will attach a couple pics so you can hopefully see what I am working with.
FYI......Car is a 68 notch with 451 originally a 318 auto car.