Hi, thanks for the hints. The car was built on Dec 1st, 1967
Were the 289 c-code factory single exhaust cars? I was pretty sure only the inline 6 were single.
Don't know about the floor replacement by previous owners, as I bought the car, the floor was already badly rusted, but mostly in the front, not in the rear/ under seat area. As I bought it it also came with the dual exhaust.