First off, welcome.
The answer to your question is no, there are no new 289CID engines available, only rebuilt ones, and that's a qualified answer. You can get a 289CID engine rebuilt here for about $2000 (maybe up to $2500) but off the shelf, ready to go, 289CID engine don't exist. There are 302CID "crate" engines available from many suppliers however. The differences are not major.
Jim