Well you have a decision to make. If you wanna go for the Signal Sil-Eightys, then yeah you need a S15 front end conversion and type x tails/bumper. The money involved in this though could be more than investing in a S14 and converting only the front end. Personally I think the second option would look better, but it's all up to you. In the FAQ there is a shitload of info on how to do this, but a good site for you is
here.