Hey Shaks, definitely rare-ish items to come across (sedan specific kits). I am not so much in-the-know about the 34, but the first kits that come to mind are the URAS D1 (and similar) kits that you will find on the famous ER34 Blitz drift car. I personally think they look shit.
Standard rear bumper with some rear pods might finish the look off for you. Sometimes less is more.
Some nice 8.5 - 10 inch wheels, lowered, you'll have a nice looking 34.