Manual rack on TC???

Yes, it should fit. The Tbird inner tie rods are about an inch longer I think. The Mustang ones will probably actually fit and go together, but would not have enough thread engagement to be safe. I would not use them.

I did the opposite, putting a long rack assembly for a Tbird on my Capri many years ago. It was too wide. I fixed it by bottom tapping the Mustang outer tie rods so the longer Tbird inners would thread in far enough to get it aligned.

Probably just swap the Tbird inners to the new rack and its done.