Or you could kick it old school. The '61 one ton trucks (C-30) had a vacuum booster mounted to the frame under the driver side of the cab. Check your Service Manual for repair and hookup. LMC sells them brand new without a core charge for reasonable money and then you won't have to screw around with the Dual MC issue.
And yes, they do help. But your basic brake system should be right on the money first. it will not correct a bad setup. It only allows the use of less pedal pressure for the same amount of braking.
