If I'm not mistaken, MS released a update that included that KB file you're referring to. After you re-installed 8, did you get all the MS updates for the OS? I've installed 8 pro on my laptop, had it on there for a few months, fully updated and just waited for the 8.1 upgrade to be released. When it was released at 7 am EST, it showed up in my store app at 7:01 am EST. I didn't have to download a special KB file to get the 8.1 upgrade.
AB, that link you posted is to purchase windows 8.1 not to download the ISO. This one is more appropriate......
No you don't! With that link I provided you can download the the upgrade, turn it into a ISO or a bootable USB and then preform a clean install. It's how most of us did a clean install of 8 to 8.1. Did you even open the link and follow the pictures.....look at spot, see spot run, see spot download ISO, see spot clean install windows 8.1 with ISO......Well if you want to do a full install of Windows 8.1 that's what you've got to do, buy it.