Are you sure the noise is coming from the front?
Could it be that the front or rear sprockets are worn, look like ocean waves, and when the bike is moved backwards the chain is "clicking" because it is not rotating in the normal direction. I'm not suggesting that you are wrong with the bearings being worn. Just trying to think of some other possibilities that could cause the noise before you spend money and start chasing it issue with adding parts that may not fix the issue.
Anyone else have something to add?
Kevin
edit: Because it is a unitized bearing and if it is worn out. Then you should be able to feel quite a bit of "wobble" at the axle if it is toast. Check this by lifting the bike if you can then grab the wheel at each end and rock it back and forth in a perpendicular direction to the axle. Does that make sense? Sorry, hard to explain without pics.