If you want it to stop then do a search on fitting a small Jap 120y type vaccum Booster as that will solve the hard pedal effort you are probably feeling,Simple basic old school step one for a 1200,Surprised nobody else pointed that out first.

As for the Color that is a bonus few are aware of,Certain colors such as Green back in the Day had a much higher lead content in the paint which allowed much better sealing to occur against the elements.

Most cars back then were painted in Acrylic paint which requires constant waxing or a weatherproof storage to stop moisture getting through the paint causing rust.

Greens some darker Blues and some Orange paints used a much higher percentage of Lead in the paint and the Lead allowed those colors to seal against moisture much better so cars with certain colors are much more likely to be found with no or minimal rust simply because of the paint color and it's lead content being much higher than other colors.