That looks real nice.

So much of it is original and in good condition, go slowly on thinking about changes.

Clean it up and tune it and do regular/standard maintenance.

Buy a reproduction Shop Manual and Owner's Manual (there are Tech Tips here for new owners, and for many aspects of owning/using/fixing these trucks). Jim Carter Truck Parts, ClassicParts.com, Chevs of the 40s, etc . .

Here is an on-line 1958 Master Parts & Accessories Catalog.

Congratulations.