The number 15 above is DISTRIBUTOR degrees which means that you are getting THIRTY (30) at the crank. This is a VERY long and would have been slow "smog" advance
Somewhere I read (cannot confirm) that the Mopar adjustable weights actually gave trouble, something about being twitchy because of the construction of the mechanism............I can't confirm or deny
Ideally you want to determine what the engine wants for total.
Dyno, G-tech, or other instrumentation, or the "old way......" strip times
And determine what the engine wants for initial.
Those two points will determine your curve LENGTH
Springs are "in the middle" IE too much advance too soon will cause knock / ping at low/ med RPM too slow won't give you the power you want. I'd start about 2500 for "all in" but you'll likely get a whole range of answers.