As stated above you can use the 3431102 1971 B-body 3 speed arm in place of the 3 speed E-body 2822293 arm and it will work...I have done it.
There is an ever so slightly different bend on the 3431102 arm and the one end is slightly different but both function as they should for 3 speed conversion on either.
Pictured E-body on top B-body on bottom