I went throught the same thing with a '39 Packard several years ago for the same reason. Be very careful which size master cylinder piston size you choose. Bigger than 1" will not stop you with drum brakes. Pistons >1" are for disc systems. It will take some looking around for a 3/4" to 7/8" master cylinder that has the deep hole for a long rod (manual) versus the short rod used on booster type systems. Hope this helps.
