yeah you would probably have to do some sort of detection as the game id part (WUP-XXXX) part shifts depending on if its a nes or snes rom too, but the wup header itself is always the same length.....to have a better look at the header you can download the amiibo classics game from the eshop, it has a bunch of roms you can look at to compare headers
Thanks, I'll probably look into it.