the 93+ Thunderbird seats look almost like they belong in a 46-48 Ford.
They were comfortable to me as well----in both of my 'Birds
(bought a 94 new---liked it so much I added the 97 later----drove these cars to DEATH)
They might fit well in an earlier model
Another option----if space is limited, might be the seats from a Mitsubishi
Galant or similar----a bit narrower and even the 4dr seats will tilt forward for rear access if needed.
Just a thought