Wayne, there is no requirement in TX to actually use a vintage block. As long as you have the green sheet from the inspection, that is what they need. Your insurance card needs to describe the vehicle as a 1965 Ford Cobra Replica, or similar words.
You do have to fill out all the TX state forms. I presume you have read that thread. You will need your FFR MSO, your FFR receipt for the kit and receipts for major components like engine and tranny. Then you will provide a tracing of your chassis number, which will become the VIN. One of the forms is where you certify that you assembled the car.
When your title is done it will say "2011 ASVE" and like Max says, it will have a comment "1965 Ford Replica."
BTW, one thing about TX Registration is absolutely consistent, no matter where you get it done .. it is completely inconsistent
Sam