Thanks for the replies and feedback. Right now I'm still on the fence when it comes to this subject, as the factory's Engineering Illustrations show that the Q-clamp was introduced as an "optional" clamp on 8/28/68. Just because some paperwork lists Q-clamps as possibly being in use doesn't mean that was actually the case.
Like John, I've seen U-clamps on original-exhaust cars (Daytonas) too, however there aren't too many such cars still in existence and I haven't seen enough such cars (not necessary Daytonas) to form a definitive opinion... hence my question.
Any more thoughts or examples anyone?