The seats i have swapped out for a set from a Toyota Yaris. They are much comfier and as luck would have it were an almost direct fit. I just cut some locating pins off and had a mate weld some bars to the bottom to allow me to bolt them down. I used all existing holes. They sit about an inch higher than standard which means my head is a little close to the lining but not dangerously so. no bobble hats for me though.
The headlining of the whole truck was rank. I pulled it all out, dried it, ripped off all the vinyl and used a combo of mastic paint and driveway bitumen paint. to re-seal it all which also stiffened it back up.
To finish it i used some truck bed paint which gives a nice matt finish with a slightly rough texture. I'm still in the process of fitting it but it looks much nicer than it did before. I'll chcuck some pics of that later.