Axle width?

This is my first of many posts that I will be making on this board.
I normally don't talk much on forums but when I do I seem to start rambling so just bear with me.
A buddy of mine has had a 67 firebird in his garage for over 20 years.
I have been slowly getting him motivated on this build.
We have rebuilt ther front end with new bushings/balljoints/disc brakes and big block springs.
He picked up a fresh 375hp 396 and turbo 400 a while back and we got it into the subframe and then he lost interest.
I am finally buying the car from him and finishing the project. This will be my 4th resurection in the last 5 years. WooHoo!

I haven't received the car yet (I need to make room in the garage for it)
I just picked up a free 8.8 rearend that I was thinking of swapping out the factory 10 bolt in the car with it but not sure of the width of the factory 10 bolt.
The 8.8 measures 60 inches wheel mount to wheel mount which seems like it might be a little wide.
Just looking into my options while I am waiting for the project to be delivered.
Enough rambling.
Thanks for looking at this post,
Ken