The following line seems strange:
atmega328bb.build.core=arduino:arduino
The other entries shipped with my Arduino environment have the following form:
atmega328bb.build.core=arduino
You may also have to provide the path to the bootloader:
atmega328bb.bootloader.path=atmega
This plus johnwasser's suggestion should give you a working boards.txt file.
I don't think you need a 16MHz crystal on the new chip when burning the bootloader. What errors do you see?