I did the whole s13 front end crap in a 70 and found there is a lot of stuff to modify, for starters you need to drill the lca bolt hole out to take the bigger s13 bolt, if your going coilovers you need to get a softer spring then an s13 runs, I had anywhere from 7-10kg springs in my teins and at the time it was cool but it got WAAAAYYYY to much bump steer, I almost got sent into someone's house cause of it,
then there is the need to up the brake master cyl cause of the bigger front calipers, the standard master can't handle it and you're foot near hits the floor before it starts to think about stopping, then comes the minimum of 14inch wheels to clear the front brakes, then redrilling the lca to take the ke70 castor rod..... There is a lot of shit to look at in doing it... Make sure you do all the research before deciding
EDIT: have a look in my thread in my signature go back Afew pages and you will find all the shit I went through fitting it