If the new core.lvl is bigger than the old one, then you're find. There's no need to fret over the differences. It means the new file has everything you need, and then some.
I use a custom core.lvl that comes at 7.25mb. The old one is was 6.9mb. The extra stuff is most likely unused anyway.
If you mean put it into a readable format, then no. Once munged the files are literally compiled into a different format from the original, then put inside the .lvl file. Anything you'd dump out wouldn't match what you started with.