Erratic Timing

Well there are several things, and factory Mopar distributors are not known for "rock steady." What are you calling "a full point?" One degree? That's NOTHING

So far as full advance, I'd say AT LEAST 3K with the big spring shown. You should be able to look that all up in the manual, if it's a stock dist and correct year. Bear in mind that the newer these dist's get the "worse" they get for slow, long "smog" advance specs

So far as spark scatter, instability, Yeh, timing chain wear, distributor intermediate shaft and bushing wear, general wear in the dist itself, bushings, advance "hat" and weights, and even the slop up and down in the shaft and the slop/ wear in the drive tang/ slot.