If it's just a multi-tap transformer then the ignition will be the first and the longest winding will be the lighting coil output I should think.  That way if the light coil burn out you would potentially not be stranded.  Does that make sense with your meter testing?  the lighting coil I would predict to have a higher resistance value

Test between brown and white and then between brown and blue, I think blue is the light and white is the ignition if the meter agrees then white goes to points and condenser and blue to the light and horn.  Next step would be to assemble and spin the motor to do a voltage test and see what comes out.