I am laughing at ADSM's obvious answer to your question...
But basically, depending on where the frame is bent and how much frame is being replaced, the best answer is to replace the frame section with a section of suitable style frame.
Your buddy has a shortbed, so if he has a single cab shortbed, he needs a single cab short bed section of frame to replace. if he has a supercab, (automatically comes with a shortbed) he needs a super cab frame section.
depending on where the bend in the frame is, you can probably use both sections from the above lists but why complicate it? this way you know if you take the same amount of frame it will work.
A longbed frame will not work because of where the axle arch and spring hangers are located. Well, ok, you can make a longbed frame work... but it involves a lot more cutting and welding and measuring
AJ