There is no better copy that I know of, since it was one of Francis Ford Coppola's earliest films and he didn't have much of a budget or even decent film stock to work with.
First off, this thread should be moved to Film and Documentary - I'm not sure how this wound up in TV.
Second, there is indeed no really "great" version of DEMENTIA 13 available on DVD yet. MGM does have good elements, including the "insanity" quiz prologue that has been absent from all PD versions. It is generally felt, though, that the most clean and watchable version is from the Roan Group; it's a 1.66 transfer originally prepared for laserdisc from a decent print.