Yes, I'd be worried about grease weeping all over the place during bake. I'd take them out, regardless, and install sealed bearings. Talk to you PC guy. He may tell you temps and give you an idea on how to proceed. You might be able to put in sealed bearings before pc, and just mask them, so you won't damage the pc trying to install them.
The rear bearing process is simple. Don't let it stop you from doing things right.