Starting a BB Duster project

I figure I'll sell it complete with the wheels and tires and driveshaft to someone with an A body who wants a complete package. It should bolt right in since it fits in my car. Just need tubs and the leafs moved under the frame.
My car is already back halved with ladder bar suspension. It currently has an 8 3/4 and the tubs are 20 inches wide. Have you measured your 60 to see what the measurement is from axle flange to axle flange?