Just had a t-top kit put in my car. Now on to finishing the inside. Does anyone have an
idea on the headliner. Does anyone make one that can be purchased?

C&C, to the best of my knowledge, used a regular old hard top headliner. They simply cut out the "glass" areas and wrapped and glued the headliner material to the T-Top frame. It was then covered with the rubber weatherstrip (Ship through) or a thin panel (non-shipthrough)