Not sure if the aft battery location is original for a C 28, but I have owned 3 Catalinas & the C22, C 25 & C 30 all had the batteries stored as close to amidships in the center of the boat as possible for more even weight distribution. Next to water & fuel tanks, the batteries & propane tank are some of the heaviest items to stow on a boat. Propane is hard to move from the stern, as it is probably vented overbord from the stern storage locker vent. It is unsafe to store below in the main cabin. The batteries can always be relocated to a storage area below the setees in the main cabin. As two deep cells can easily weigh nearly 40 lbs a piece if they're lead acid type, this may be your aft weight culprit. Secondary anchors & dingy's stowed in the aft main locker can also add undesired weight. But as far as sailing, if I had to choose its better to have weight aft then in the bow. Excessive bow weight will cause the bow to plough into a wave in a deeper then designed angle & potentially slow the boat down. Does you boat have the original engine? During its life it may have had a heavier diesel replacement engine that could have added weight ballast. My 2 cents.