If it is the original tank then that would make it 41+ years old. Replacing it might be the way to go.
If it is confirmed to be in good condition then yes you likely can replace the the fill and bleeder valves.
Your valve might even pre-date the
Auto Stop valves. I haven't come across a filling station attendant who knows how to fill one of those yet.
Auto Stop Valve info:
http://www.classbforum.com/forums/f5...pane-1746.html