Your boom is completely different from mine. Which is why I have not chimed in earlier.

You have gotten some good advice already. I would be very careful with that. It probably could be bent back into shape very slowly with a large smooth faced wrench and a long pipe to extend the handle. A long handle will give you better control with less force.

To stop the rocking you need more surface area than washers would provide. I would suggest aluminum or stainless steel shims as large as the face of the fork.

Let us know how it turns out.