We have a 15.75 dia 3-jaw with 2 piece top jaws on our TL-3.
It is a Bison brand Set Tru style Model 9903.
I'm not sure if it was a special order, but I can find out if you want to know.
That might hold a 24 inch round with special extended top jaws. I'm not sure how stable that would be.
The other option would be a large face plate mounted on a special A6 adaptor.
We are also going to buy a TL-3W in the next 6 months and we intend to equip it with the same 15.75 3-jaw chuck.
I just found this web site. A6-15.75 is a standard