Lots of aftermarket helper springs were available from various vendors. I've got a 51 GMC long bed half ton frame with what appears to be factory overload springs installed. Not sure if the same option was available on Chevy, since I don't think a long bed half ton was available for most, if not all years in the 1950s.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!