Old Tyme Body Work

Here's hoping there's a couple of old body men, or master welders on the forum list. My Mig crapped out with my car 90% done. It is beyond repair, and I am not going to buy another. I still have half a quarter panel to replace. Should I use mild steel rod with my acetylene rig, or should I braze with brass rod? I know I have opened up old body work that had been done both ways.