I'm going to put my bilstein IX shocks up for sale shortly if anyone is interested. Making an order for the Koni fronts as soon as I get the drawings to compare some measurements
Edit.I had to reword this because it doesn't really make sense.
FWIW, If I were to put the IX shocks into E30 struts, I would cut down the housings as much as possible to gain as much bump travel as possible. Putting them into stock housings with a spacer won't really gain much. It will just end up bottoming out just like stock length inserts. Although I can't remember the lengths offhand, but if anything is gained, just the droop becomes shorter.