They are both really cool saves. I am resto modding one identical to the bottom one, but both are desirable bikes to have. I'm not even going to attempt to date anything, because there are scads of people here who know more about this stuff than I.
I can say they are both dynamite scores, however and you should have alot of fun doing whatever you are gonna do with them.
Before you do immediate paint removal, you should consider your options. Try spraying the tank bike down with a little oil and just see how much paint is under the rust, first. Wipe gently. You may come to the conclusion that you want to keep it in original finish.
These bikes have a way of looking awesome in original patina.
Don't take an angle grinder to them until you are certain you know what you want to do.