A question I should of asked before

As some of you may know I have a 70 b body 8.75

It's being narrowed to a body lengths.

I have a pair of abody 8.75 axel.shafts on the shelf from a 71/2 deamon

Will these a body axels fit inside the b body axel once narrowed to correct a body size?

Or should I get the b body axels shafts that are with it cut and resplined?