Attached are some screen shots of data I was able to find in a web search on "specs" for the '58 front springs (found at https://www.truckspring.com/
) that may help you confirm these springs are correct for your planned use. I used the original GM Part Number "3719560" from a Chevy Master Parts Catalog and your vehicle info to help locate these tidbits.
Also included their diagram on how/where to take measurements of your springs to help compare with the listed spring specs. If you remeasure your springs and the numbers match these specs (A and B lengths, width, spring stack thickness and Arch height) you may be able to ring the "winner-winner-chicken dinner bell". (Just an educated guess on my part.)
Let us know what you figure out.
PS: Also included a snap of the rear spring data in case you may need that down the road.