DSC02649.JPGThe stock mirror will let you see out the back window. The trucks came with side mirrors also and many folks added big side mirrors. We can't tell you what visibilty level is good for your eyes. You will just have to add or modify until you are happy. Now that I see you are not trying to stay purist original, there are endless aftermarket mirror options to choose from.
My 1960 4x4 Big Window short bed 305 V6 custom cab shown was sold a few years ago. After market side mirrors.