>>321342572
74mm IPD here, yeah that's the trick. Just don't get foam that pushes it too hard that it tilts, but yours is fine then. You can adjust it a little better with this mod:

Open "C:\Program Files (x86)\Steam\config\steamvr.vrsettings" in a text editor
Add the following line under "steamvr" : {

"ipdOffset" : 0.003,

And that adds an addition 3mm on top of your max of 70 for the Index in software.