I have let this one soak i for a day or two before replying..
Something i have learned over the years (60 plus years with cars) is that the factory is going to do everything they can to make the product ( in this case a gasoline engine) the very best they can .
The top of the line line flatheads from the factory ran 11 degrees ( 22 degrees engine ) of spark advance at 2500 rpm . Some early models ran 8 degrees ( 16 engine) .
Now if we take that as the desired rate then why change it ?? The video shown here shows the effects of taking advance out of the engine , losing torque and hp.
SO no matter what ya do to the engine this base line doesnt really change !
We spent a fortune on our Bonneville engine to make 181 hp at 4300 rpm while my friend down the street is making over 1000 hp with twin turbo monster mustang !!!
Just clean it up, make it the best it can be and go on !
I am getting ready to take a look at some of these jap ignitions based on the look as well for a customer will report when done .......