Hi Carl,
A few years back, I lost a trim tab. I did not want to give up the recessed tabs, so I had a new one made out of fiberglass. While I was at it, I got rid of the internal jack screw actuators and replaced them with Bennet hydraulic. They work MUCH better than the old jack screws. You are lucky that you have both original tabs still in place. If the trailing edge of your tabs stick out beyond the transom, you might be able to attach some Bennet hydraulic actuators. I would consider this before you try removing them, as the cost of removal and then filling in and farring out, could approach the cost of Bennet actuators mounted externally. Mine work fantastic. Below is a picture. By the way, while you are at it, check the hinges. You do not want to loose one of those tabs, as it is very expensive to have new ones fabricated.
Good luck,
John Austin
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edit comment: th_ "thumbnail code" removed from image link, to bring it up to full size.