you could even change a few pieces around to make it fit a tabard easier. the alliance tabards are very purple or blue heavy so /shrug hope that was helpful in some way
edit: oh and if you get the darkmoon cape it could help match the purple alliance tabards well too and also has some green in it for the rest of the mog
click the bottom link that says "Alliance Tabards", it has side-by-side comparisons of all available F2P tabards...except the hushi/tushi/whatever tabards that came in MoP.