Here's the problem with converting them to other templates. See where the logo is placed on the spine? See those umbrella symbols at the top? Well, since the gamecube's spine logo is located on the bottom, and the playstation, wii, dreamcast, etc, is located on the top, it makes it very difficult, if not altogether impossible to do a good template conversion while keeping the series uniform.
I'm a bit too busy to tackle something like what you want unfortunately. You're asking me to essentially remake the covers from scratch, which kinda kills the point. If someone else wants to try a PAL conversion or something, that's fine with me.