If Al doesn't have it or hasn't seen it then it likely doesn't exist.
I went back and looked at all 24 of my Milton Bradley 1968 AL #10 cards. None have the Lonberg variation on the back. By scarcity I believe this was corrected in the regular 68 series about 2/5 of the way through the regular print run (by early 1968). I think the value is about 2:3 which is what I am basing my guess on.