Didn't you just say yourself:
Or you can limit the mech advance travel stop to about 10deg of travel.
This will allow a 24-26deg inital base timing at idle.
and a total mechanical advance of 340-36deg at max mech advance.
use a 1 medium and 1 light mech advnnce spring combo once the mech advance travel is limited.
BTW that's total
advance, not "total mechanical advance". Total is mechanical plus initial. Mechanical is the 10 degrees that comes in from the weights. Initial is the 24-26 degrees, the two added together is the total advance.