Willowbeen,
Welcome to the Stovebolt!
Did you replace ALL of the steel lines? They rust out from the inside...do you have a small leak in one of them or at a wheel cylinder?
Did you adjust the brake shoes? If they are to far away from the drum you have to pump the pedal...
Are you bleeding the system in the right order starting at the Hydrovac...do a search here, this has been covered many times.
Lastchance towing posted the bleeding order in this very thread...check it out about 8 posts before your's if this link doesn't work.
http://s185.photobucket.com/user/uffeg/media/20130817_175503_zpsfcd15062.jpg.htmlThe 1959 Chevy Truck Shop Manual should have all the info you need.
Mike B
