Thanks, guys. I am having second thoughts about the heat method, as I
do believe that it will make the surface wavy and odd shaped. I do
know for sure that weight applied with a forklift and jacks/chains,
will flatten the surface acceptably. Given this knowledge, I will just
pull the surface from below using a welded on allthread and a
brace/nut, pulling the plate down using a C channel as a brace. It
should work. I have a 3/4" allthread available.