Which UART you are using - DUART or QE UART?
The main advantage of the DMA is that DMA and Core can access the SDRAM simultaneously. The DMA has the advantage that it can execute bursts on the bus.
It reduces utilization of the core.
See attached file. It is simple program example for DUART FIFO using on the MPC8349.
Similar code can be used on the MPC8306.