What size head pipes and tail pipes used on the factory '68 340?

I have owned two '68 cuda factory BB cars, still wearing the original exhaust. After examining these cars and long talks with Accurate Exhaust I have come to this conclusion. While both of my cars have full 1 7/8" systems (the tips are 1 7/8"), the existence of NOS pieces in 2 1/4" leads me to believe that the factory used whatever parts that were available at the time. A person can debate this subject all they want, but there is no conclusive answer. If you feel that the system was 2 1/4", then you have to accept that after going over the rear end the tailpipe must reduce to 1 7/8" to fit the chrome tips. The judgement call is yours. For me and my "correct" restoration, I went with a full system from Accurate, 2 1/4" all the way including 2 1/4" tips. So much for being "correct".