Install honda cd 100 headlight. Why I am saying is reason 1 it also have good focus as I have honda cd 100 bike so can tell truth. Reason 2 it will be definitely cheaper than yb125z. Reason 3 it will fit bolt on bolt after removing screen of pridor. Reason 4 it's also round as you wanted.
You just have to check that light you are going to buy should be genuine from any honda parts shop. Because after market might have low quality chrome and glass so can't produce quality light.