The LM338 can be used for any input voltage if the difference between input and output voltage does not exceed 40V. So for a desired output voltage of 60V the maximum input voltage of 100V is allowed, but not recommended because of the high power dissipation within the chip.
However, the max output voltage is limited to 32V. Further the maximum current is 7A.
With other words, you can't use the LM338 at all to charge a 48V battery at 30A.
I suggest you consider a solution using several paralleled power MosFet transistors and adjust the gate voltage for a maximum of 52.8V to float charge the battery to that absolut maximum voltage at your desired maximum charging current.
Boncuk