Raccool That depends on what format the files are in. If those are .lrf files in the old first-person format, you won't be able to watch them unfortunately. If they're in spectator format however, they should be watchable. Whether or not uploading to the website will show stats depends on whether they are embedded in the replay file or not.
The easiest way to try this is to place the .lrf file in LoLReplay2's "replays" folder (at "...\Documents\LoLReplay2" by default), and restart the tool. It will then either move the file to the "old format" directory (which means you're out of luck), or it will add the match to your match list. In case it does that, you should be able to start it. If you get this far, patching should take quite some time, but it should theoretically work.
If you're having any issues you can also send me the file to firstname.lastname@example.org and I'll have a look.