that is called "scarf joint" headstock. haven't tried it yet but i've heard that works great..! gotta try it sometime... do a search here on the nation and you may find a few and how to cut them in an easy way..!
I figured out how to cut and glue my head stock to make that angle. I measure 6 inches from the top back of the piece of wood across to the frount l\l like that. I turn the cut piece over and glue it back on. Works great.
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