Welcome to the Forums and the world of Vintage Ambassador ownership!
If you are looking between the entry door and the front of the coach, there usually is an emblem designating the model and VIN -- further down the side of the coach, there may have been an emblem designating the International model -- some dealers added a cast emblem that may have been removed over time. More details about location of the suspicious rivets would help with positive identification.
Good luck with your Ambassador!
Kevin D. Allen
WBCCI (Lifetime Member)/VAC/Free Wheelers #6359
1964 Overlander International/1999 GMC K2500 Suburban (7400 VORTEC/4.11 Differentials)
1978 Argosy Minuet 6.0 Metre/1975 Cadillac Eldorado Convertible (8.2 Liter V8/2.70 Final Drive)