I can't help much but I think the 'INOXYDABLE' sticker means it is a PX series bike. I think your guess of 64-67 is pretty close. Are there any mounts for a chainguard? It looks like some of the components have been changed over the years but no surprise there - the bike is almost 50 years old. I know the fenders, brakes and lights were all different in the 50's but I'm not sure what year the changes occurred.
In any event, it is a fine looking bike!