Selecting correct offline update file for iPad 2
iClarified just links to IPSW files hosted by Apple (note the apple.com URLs), so it's a reasonable place to find links to download these files.

Yes, #2 sounds like the correct choice for you. (Note that if you choose the wrong IPSW, iTunes will just give you an error message and not restore the device to it. And even if you could theoretically restore to the wrong IPSW, you can always start over and restore it again.)