I had the same problem on my hood sides after welding on the mounting brackets.

I always heard that the stainless steel heat shrinking disks placed in a large disk grinder worked wonders. I bought one and was amazed at how well it worked. It really focuses the heat and was easy for me to work the dent out. One thing is they will only shrink a "high spot" down, not raise a low spot. But on a hood you have the ability to get to both sides unlike working a door panel.