The '67 right side tube is shorter and the check valve is completely different and will work without cleanace issues. It' bends off on 2-45 degree angles. The '68 tube is taller and won't work like that.
It's just the way it is. Back in the day, no one ran smog and a cowl plenum AC. My Chevelle was two weeks old when I ripped off the smog and threw it in the trash.