There are some great videos on YouTube about the guitar tone Norman Greenbaum came up with for Spirit in the Sky (a fairly recent re-recording was noted by the band contacting him to get the exact amp/guitar settings originally used in the studio).
When the song first appeared on AM radio it was unlike anything I'd ever heard....so catchy...never get tired of it; however, back in the day, I considered the rest of the album boring and was glad I never sprung for it.
Regarding old recordings, if you haven't heard Robert Johnson - The Centennial Collection you're missing something special.
The studio wizards have resurrected 1930's portable tape recordings and rendered them entirely listenable...by today's standards!
It goes to show how far the remastering/remixing arts have advanced.