Strut bump stop help?

[911s55]

Just installed Bilstein HD shocks and strut inserts in my '71 Targa. When trying to bolt up the top mount on the strut I couldn't get enough threads to come through to fasten. I jacked under balljoint and all that did was lift the whole car. I removed the triple stack rubber damper and left the single ones that secure under and on top of fender well. With that set up I have about half an inch of thread remaining on top of nut. The strut insert comes with a small rubber bumper on top of insert. Strut cover is snug against bumper inside fender. What's up, potential issues?
Thanks, David