Lessee, 14.25 undermount sink, at _least_ 2 inches for the fixture,
depending on the user interface, plus some buffer for the mounting
hardware, let's say 3 inches, your overhang(3/4 inch), and room for
the undermount to clear the vanity (1/2), plus the thickness of your
vanity carcass I'd say 20 inches for your top. So 19.25 inches for the
vanity depth. I think. Tom