Welcome to the forums!
Congrats on your new to you airstream! Wow! I sure hope you do something great for your friend! Wonderful gift!
A 58 will likely have some different issues than we had with our 1963, our 55 is still in pieces... but you might check my husband's thread he has lots of pics of what he went through and lots of how-to's!
If you gut the trailer and decide to "modernize" the interior parts, beds, cabinets, appliances, etc. Before you throw them away, be sure and post them in the classifieds! Many folks are looking for items that just might be in your "trash"! Often times patterns are all that are needed! Other items that are not so clean, or that likely not working appliance may have the one part someone needs! Even knobs and sliders, etc. So if you decide you want to rid yourself of the old stuff, post pics in the classifieds and you might be surprised on the responses you receive!
Good luck and post pictures soon!
Mrs. NorCal Bambi (traveling in S Tardis ~ from the Great State of Jefferson)