So I did a search but found nothing wich helped answering my question: if I modify the body to accept the 3-bolt EJ front strut mount but keep the EA81 suspension arms modified to fit the EJ ball joint and knuckle, will the EJ strut and spring clear the EA81 body (especially aorund the spring seat, seen cross car)?

the short answer is no....

 

i had impreza struts/springs in my brumby (brat) and even after i "stretched" the inside of the tower as far as i was game to the spring coils still hit the outboard bottom of the tower where it rolls around at the base....i now have a set of adjustable tein shocks in the front with a spring retainer/bearing carrier that i made up to allow it to work properly with the ea81 strut cap

OK. I will make my own pillow ball top mount and will use the EA81 spring on a modified EJ strut.

if your making your own adapter for the strut top make some provision for altering the ride height....the stock length impreza struts i had in made my ute run really low in the front....and they where soft as hell too compared to the ea81 setup