69gtconv: Are you just trying to repair the bar or are you trying to modify it to fit headers,etc?
I have been through this process, and I did it myself. If you are trying to repair the bar, then you probably want to start with a new one. In my experience, once it bends, it looses its strength and will bend again.
If you have a really strong after-market clutch, you may need to re-enforce the bar. I ended up getting a new one from Dallas Mustang. Bending it to the appropriate shape, then sandwiched the bar with 1/8" steel for strength. No problems now.
I also did this little modification to make it easier to install. Note, this is the first z-bar I modified, and the second one looks much better.
(i fixed the link)