You're breadboard with a '328P - which datasheet did you think I was referring to? Perhaps you've seen it?
In boards.txt, change the LOW fuse byte the Uno entry to:
In section 28 of the datasheet,
Table 28-9. Fuse Low Byte
I don't know what you're looking at, perhaps the Summary datasheet and not the Complete datasheet?
Use a Programmer to burn the Uno bootloader onto the board.