Which drums do I need?

I'm converting my ‘66 Barracuda from the sbp, to 5x4.5. On the front, I just did a disc conversion. On the rear I installed new Yukon axel shafts, with the new bolt pattern, but using the original drum breaks. Does anyone know where I can get a drum to fit? Either a new part, or a drum off another model that will fit the bill. If all else fails, I can pay a machine shop to rework the originals, but they will need a new bp & bigger center hole for the new axel shafts. Thanks in advance!!