The vast majority 68D's are pretty horrible. It was the last year for the master obverse hub and it was extremely worn. All 1968's are mushy because of the hub's poor condition.
I hope to someday submit mine, I think it has a good chance at 67, 67+ or possibly the top-pop 68 (which currently PCGS has none).I struggled finding a nice one for years. Then I met Ben Peters, an old timer that had been searching memorial cents for decades.
He was the most avid Memorial cent guy I've known! Quite a few of my coins came from Ben.