Noone will even see the back of your mouth trying to save a molar is a waste of money,and it could lead to more problems later on.
BTW i'm saying this because i had a back molar and a wisdom tooth extracted about 2 months ago.
One was roott canaled and filled with amalgam to the root,so my only option was extraction and removal of the periodontal nerve and cleaning of the underlying tissue to lower ridk of future cavitation.
I than had to have the wisdom tooth removed because of nerve damage form having the other tooth extracted,along with it having a deep filling.