I bought a 89 lincoln mark VII as a donor which is very similar to the t-bird.
The engine is great. It is fords High Output 302 with a roller cam, forged pistons and rods, truck heads. The lincoln does not have a MASS air sensor but can be upgraded with a sensor, wiring kit and computer from a mustang for $150 if you want to add nitrous or a supercharger/turbocharger.
The transmission needs a cross member to mount. The AOD isn't the strongest transmission in the world, but it is overdrive.
The rear end is an 8.8' where i'm getting a granada 9" but ive seen a bracket for $90 that will bolt up the disc brakes to the 9".
On the lincoln which is probably the same on the t-bird are used as donor cars. The front A-arms and it has the large (11"?) brakes. So there may be a few parts you can unload on . The t-bird is wider than a fox bodied mustang so the rear end is too wide.
The lincoln has other things like anti lock brakes that i'm not really sure what i want to do with.
I picked my lincoln up for $600 at auction. I'de go up to a $1,000 at auction, perhaps a bit more for the right one.