OP doesn't mention what engine.
64 Chrysler FSM says 34-40 degrees for both, 27-32 individually, 413 engine
65 Plymouth FSM says 36-40 degrees for both, 27-31 individually, 273, 426W
69 Dodge FSM says 37-42 degrees for both, 27-32 individually, 340, 383, 428, 440 engine
so it varies a touch depending on the year, but probably not enough to matter. I like to shoot for the center of the range and you really should have an FSM as it talks about how to set it and how to check for dwell variance.
http://www.mymopar.com/index.php?pid=31