At Ed Cunneen's suggestion I went through Chicago Corvette Supply for my dated 4346 and was very happy. You need to talk to Al Ferke.
There are a couple of bell housings on eBay:
Bell Housings
And you might check in with board member "Yountto" for heads. He seems to have a lot of dated stuff, some of which he is selling on eBay under the same user name.