I will have to do a little figuring and see if shorter than 51.4" ( stock A body length) gives me an advantage. Im building this thing for road racing and as is it will take a very large tire since I minitubbed it.
Andrew
Stock A 8.75's aren't 51.4". They are 52 5/8" +/- a smidge
Never seen a A body rear in a 68-72 car have a track width of 55.6 like in the other link, re: everything you ever... All have been 57 1/8.
Be careful with the info on the net. Some of it is very wrong.
Minitubbing, you'll be better off with a shorter rear for wheel offset. Stock length you need a 15x10 with 7.25" backspace, or right around there. Most of the cars I end up working on have rears from 48" to 52" total width. my Duster has a 50.5" rear, 15x10 with 4.5" BS IIRC.