Progress has been slow as life gets in the way...I located a Capri rear axle which was going to be all that I needed for this project until I actually saw what appeared to be a large ball of rust connected to two smaller balls of rust, none of which wanted to move in either direction and was not quite as advertised so the hunt has now switched to a first gen Mazda RX7 rear axle...
 
Don't hold your breath waiting for this part - as I said, life gets in the way.