Ive got a 91 240 and I believe there is 2 different models, one with flip up headlights and the one with the regular headlights (correct me if I am wrong) but my question is, how hard is it to conver the flip up headlight front end to the regular headlight front end? Thank you.

 

In the US there is only one front end. Do a search for Silvia front end conversion, tons of threads on it, hell search google and get tons of answers, pics, whatever you want.