I also remember a few years ago when i was cleaning 50+ years of dirt and grime of the chassis, that I came across serveral parts and labels with 1958 stamped on them.(in those days shipping to Australia would of taken 6 months) I will have a look over the weekend if I can refind them again. Is it the original engine? If so, the engine block should be stamped with a date.
Pull her apart and she shall reveal her birth date