Front or Back??

Came factory on the front. IIRC. But I like to put them on the back my self. It is a what ever kind of thing.

Yes, the 73-76 A Body single piston calipers came from the factory, mounted to the front.
The 65-72 Kelsey Hayes calipers were mounted to the rear.
On your conversion it really doesn't matter which way you mount them, as long as you use a rubber hose that works for the caliper location, front, or rear.