As of the Advanced Class Guide there's a Magnus archetype that's a spontaneous caster with it's spells revolving around CHA instead of INT.
http://www.d20pfsrd.com/classes/base-classes/magus/archetypes/paizo---magus -archetypes/eldritch-scion
Angel-blooded Aasimar's get a bonus to STR and CHA, so this might give Aasimar magnus' a much better build.