70/70 struts are smaller in every dimension. theyre smaller tubes so inserts you can use in an 86 wont work in a 71. the brakes are smaller, and also the bolt spacing on the steering knuckle is differant, so you need to change those aswell if you do get some 86 struts. think the stud axle is a little smaller too.
so you you wanna/kinda have to change to 86 struts to set the car up properly/be able to do all the regular mods.