That carrier is in terrible condition. I'd want to start with a complete center housing from a donor rear end and scrap the entire center section you've got there. There's no telling how much load has been put on the housing casting, or how many stress cracks there might be in it, just waiting to destroy all your hard work and expense of a rebuild job. These rear ends aren't that scarce, as the same assembly was used for a range of several years from the mid-1950's to early 60's.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!