How to make a correct transition from Bar-Boss-Bar (Drag Link Forging)?

Hello all,
I need to make a Boss as shown in image attach.
- Dimensions shown are necessary.
- Transition needs to be adapt to a bar of 1.000 inch.
Does anyone know any technic to model this transitions?
Or know a book, file, page or tutorial that show a technic to model it?
If someone needs more details to give a suggestion, please feel free to let me know.
I will be pending for your answers.
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SB