There is no upper bound to the amount of overflow. Imagine a glass with generating angle very close to 90°. In order to have depthh, it will have to be immensely wide and therefore have an enormous capacity. If a huge ball is (very carefully) lowered into it, the amount of liquid displaced can be arbitrarily large.

If you want a more mathematical argument, notice that the critical value forxfound in the previous thread has a denominator which goes to 0 as approaches 90°. You can check that the same denominator occurs in the expression for the greatest overflow.