Leave the historic mural.
I grew up in Penetang and often visit ( Pioneer Days etc. ) I now live in Victoria BC where heritage is valued. Yes there are old & new ads etc. painted on buildings and the a re respected and left to weather.
There are a lot of posts on Face Book about preserving the mural - changing it will be costly and ' not green ' sure if the owner decides to change, ok - but in the mean time - let us all continnue to love it ( check out Chermainous BC " the Little Town that Grew " which is famous for murals painted on its buildings