How to determine the RPM for all in?

If it doesn't rattle leave it alone. Back in the day when I ran points I took the springs off and let the point drag close the weights so it would start.

Early timing doesn't hurt as long as it isn't rattling.
True that. Unless you are class racing and need to squeeze every last horse out of that Magnum, as long as it doesn't ping and runs good I wouldn't mess with it. Unless you like to mess with that stuff. You can dink with it and may-be go the wrong direction and will have to go through the work to change it all back.