If you have to break the cam in just crank it up to where the starter will handle it. Maybe 25*. If you are cranking it and it doesn't fire right away, keep feeding it advance til it fires then set it around ~35* at 2500 ish rpm during break in .
Most important is to get it fired and up to RPM, then worry about timing numbers. You want to get it up on timing FAST so it isn't running retarded = hot exhaust tubes
Have the carb primed too, so you aren't cranking it over waiting on a mechanical pump to feed it. If a DP, fill that side too and press the pump arm to keep it running until a mechanical pump catches up. Electric pump this isn't an issue. Get them filled and set bowl levels.
Good luck.