Sliding seats? Reclining seats???
I can move the backrest on my '76 forward, but that's as far as it goes with the bench style seat. However, fully back is at the nice upright angle I like. With the older car I have more room in the transmission tunnel area so out on the open road I get left foot flat on floor with leg propped against tunnel, and for variety tucked under as per automatic style.
The seat base on the drivers side is going a bit soft, but I've found for longer trips adding a 3/4" piece of packing foam has solved the motorcycle bum syndrome

. One day I'll get around to redoing the seat foam (on the driver's side

).
Cheers,