Frame question

[1970cst/10]

I finally figured out why my hood and fender would not quite line up. When I removed the whole front end I found that the right side frame rail was bent in about 2-3 inches and about a inch on the left. The truck obviously got hit at some point and when it did it bent the core support also. The PO just shimmed the fender out with some 3/4" so everything just would not line up. My question is what is the best way to straighten the frame rail? Here is a pic of the left side from above.