j.b. weld or marine tex will not hold up,don't waste your time.there is to much flex on a t-top,s.s. toggles will be the easiest fix.the strongest fix would be get2 access covers from west marine or where ever and install 1 on each side in the floor.you will have to cut 2 holes in the floor.then you can use bolts with large washers under neath.before cutting into the floor make sure your gas tank is not underneath.
Let me make you 2 oversize plates. Slid them under the two front leg plates and drill and tap you old plates mounting holes into them, them shoot new screw holes outside the old holes into the deck. Back the screws back out and pump the new holes full of 3m 5200. This will seal the new holes and act as thread locker on the new screws. About $10 for the plates. Tim