Becker NA is still alive and well in NJ with tons of radios, parts and service readily available here's their website: index
FWIW... your '74 Berlina would look much more authentic (if that matters to you) with a Becker Europa II stereo radio. They are available through Becker NA (rebuilt) and eBay quite regularly ($200 can score a nice one). Easily Ipod compatible. Just plug a wire in back (available through Becker NA for $50).
For now the dash has been hacked to accept a standard DIN radio. As I'm "restoring" this Berlina on the cheap for now, I'm just looking for a DIN radio that doesn't constantly cut out, and I'm happy to use a cassette adapter for my ipod for now since the Berlina is pretty loud.