Ok, so, in the front you need to have a 5.25" to 5.6" backspace with a 17" rim. Both wheels have options, the AR's have a 17x8 with a 5.625" backspace that should work, the Coys have an 18x8 with a 5.5" backspace. Either should work in the front.
In the back it depends on a couple things. You say you have an 8 3/4 axle, but that would not have been stock for a '75 A-body. Do you know the width of the rear axle? Does it have the 5x4.5" bolt pattern? 8 3/4's come in a bunch of different widths, which will determine the backspace you need.
