interior swap out on a 65

[65GMCFirstride]

Hi i recently bought my first car a 1965 GMc truck and i am currently working on the cab and am almost finished, it ame with the original bench seats with no seatbelts. I am swapping the seats out with newer ones posibly from a newer car with a more modren look, such as leather bucket seats from a 99 surburban or smething like that. i want to keep it era correct but at the same time give it some modren feel as well. any ideas