what are "guards"

if that's Kiwi for fenders, generally the 55-59 ["Task Force" series] share nearly everything
except the front fenders, hoods and grills, and for a couple reasons the fenders are not interchangeable without changing the whole front clip
the 58/9 frame is a couple inches longer then the 5-7 frame [
see here], the grill surround is totally different, the top inside of the fenders are a bit different curve because wider at front, as is the hood shape to fit the fenders and the hood hinges attach differently .... so short answer, "false"

Bill