1964 Chrysler 300k rocker panel rust

So, Im thinking this is going to be the biggest problem to tackle on my 300k. I purchased this car with a great 2-tone paint job and for the most part the body is in great shape. HOWEVER, a lot of rust bubbles are forming under the paint on the rocker panels. I'm assuming the previous owner did not do the proper body work under this paint job.

Now, whats my options as far as fixing this issue? I tried looking for direct replacement rockers online but could not find any for this car....

1964 Chrysler 300k rocker panel rust