Roller Rockers 1.5 vs 1.6

Thats not to say that changing the rocker ratio won’t have any affect on V/P clearance...... it does.
But minimally.

In the OP’s example.... xe268 cam, in at 106.
The lobe lift at TDC is .070”, so valve lift with a 1.5 would theoretically be .105”.
And with a 1.6 rocker....... .112”.
So...... you lose .007” clearance.