Wait, the collage photo Is the Ican fl1
i must be trippin when i was seeing the pics
it seems like the fl1 headtube bearing seat were built anticipating the super thicc fsa acr style c-ring.
while stacking 1-2mm spacers may do the trick, i can see that having proper c-ring might be better under the dustcap as the ring width is wider to support the dustcap flat in place
my ICR c-ring+topbearing vs tantan c-ring+topbearing.
the ICR one is thicker indeed