c clamp a buck plate for the under side, . air hammer with a flat 1in head, that you can concave (ream out with reamer bit)to make into a round head , just did mine last week,,, , put the round head in from under side, heat redddd hotttt and drive it home from the top,,, it will be round on both sides ,, per henry ! ps. oh, like ford38v8 said one at a time