'73 up drum to disc conversion track width change

Just an aside- a 65-67 B body 8 3/4 axle is a great upgrade, is literally a drop in (aside from drive shaft shortening), and actually puts the rear track almost exactly even with a disk brake front track.
No, not entirely true.
The B body axle had the spring mounts at 44” center to center. The A body is 43”. I’ve heard of dudes just spreading the leaf springs to mount a B axle but to me, that is a hack move for dudes that don’t have a welder.