Hiya Ken Marks! So good to hear from you, my friend! I'm doing just fine and truly hope you are as well.
To answer your question, yes, my 1962 JELL-O Roger Maris blackberry box is of the three-ounce variety. I even went to my safe and finally got it out to confirm. I don't know if you happened to view the other unfolded box I am very privileged to own, but to give you an idea of what it looks like, there was a thread started late last year on the postwar section, post-1980 cards. It should have been put in the pre-1980 postwar, but it is what it is. The thread was entitled, "Box Design Cards". If you look at the listing in that section of the forum, it is at least one page of threads back. My son mind you, was able to sequester an image from my forthcoming book on postwar regionals and load it up to that thread. The actual photo on the CD book is even clearer, but my point is that the Roger Maris box looks the same as the Mantle.
I've said this before, but I will always be extremely grateful to you for taking the time and trouble to make exquisite color copies for me of the 1963 Post Cereal backsides that offered among its free prizes the cards of Mr. Mantle & Mr. Maris. They were used as perfect accouterments for the photo I staged of my chapter on the 1963 Post Cereal.
Would love to talk with you on the phone some time. I don't know how to send a PM on this chat forum; that's why this response may seem a bit personal. Trust I'm not offending you.
Take care, my friend.
Respectfully, Brian Powell