ignition timing question 1972 400

Update..after taking the dart out and standing on the gas somewhere around 4000rpm it had a really bad high rpm miss. That quickly verified that my timing readings were wrong(too much mechanical) turns out my aging dial timing light has issues. I purchased a new digital timing light and a factory reman dist..$50 from rock auto. I took it apart and welded up a slot. After pulling it and fine tuning the slot length im now at 15 initial and 38 total w/o advance, now it runs like it should. Thanks for all the input guys.