How much rust is too much?

SORRY but that is NOT a question anyone here can really answer for you.... THAT is a question ONLY YOU can answer...... some guys would part it out...that guy in Germany is rebuilding a car that was BY FAR and I mean FAR worse than what you have and he is doing it! AND doing a damn fine job of it based on the pics he shares with FABO.... he had A pillar rust like nobody's business...rotten clean thru and when he was done it looked like a brand new A pillar same with the firewall and the rear end....his car was not really a car when he started it was a collection of rust shaped like a car and HE is doing it....hence I cannot place a "worth" on weather it is "WORTH IT OR NOT" only YOU can do that....and obviously this isn't really about monetary value or resale value because if it was, NO ONE would do it..... I believe this is about what YOU want to accomplish....whatever you decide
Good luck