That is exactly right. You set your total timing by reving engine to point where no more timing advance occurs and set to say 35 degrees. Let of the accelerator and see where timing rest at idle. Should be around 10 degrees initial. No limiters in distributor ought to allw about 25 degrees of total advance. Should you want 15 degrees of initial advance then you need to choose the limiter that only 20 degrees of mechanical advance.