Wrong distributor for 69 318?

Hard to say. What got you to "this point?" In other words what is the story on your old one.
Are you CERTAIN about the timing? Any chance the marks are off? Is this a "dial back" light or just a straight no frills light?

NORMALLY a generic "all purpose" "replacement" distributor would NOT give you the figures you posted. Normally a every day pass car dist. would have a much longer advance curve, maybe 5 or less BTC and maybe 32 or so full advance and THAT would be quite high RPM. "Smog advance curve" in other words.

One thing would be to examine the centrifugal advance. Pull the cap and twist the rotor. IT should move freely, but against a spring, and should "spring back" counter clockwise when released

There might also be a possibility of "rotor phasing" problems. Google that term. You can easily check it with a chopped up old cap and a timing light

There has been cases when the pickup leads were reversed, and THAT will through phasing "off." China imports, who knows?