I'd similar probs a while ago and cannot for the life of me remember which i used Might have been fsa :?
Also thinking on it now I used a crank bros headset as it was the lowest i could find
Again I'm unsure of model details, but there should be threads on this here and stw.
Couldnt find the thread but here some examples on stw. https://singletrackworld.com/forum/topi ... ck-height/
I have a lower stack aheadset but also wanted a lower stack stem to really put some spacers in. It's harder to find a low stack 90mm stem. Sunline used to do the xc stem and I've seen some fsa ones. But when you need one, you can't seem to find one
Using an old Xlite to solve a too short steerer tube problem. Also take a look at some Bontrager stems as their bolts are closer together than usual so that the top bolt will bind the steerer tube.