People with good Dana's want an arm and a leg ... and then you're going to cut it up. save yourself a lot of hassle and probably some $$ and just buy and aftermarket unit built to your specs.
If you can do all the work yourself then go ahead with an old truck housing, but it will be about the same money in the long run to start off with a Strange S60 housing cut to length.
I would do a 9" if I was starting with a clean sheet
Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60