I think you have already told us that you require an output voltage which goes below the 1.2volts minimum from the LM338, so I don't understand why you are asking again if you can use the LM338.
" . . regulators capable of supplying in excess of 5A over a 1.2V to 32V output range."
I stronly recommend the excellent design presented by hotwaterwizard. I'm sure it will give you exactly the output you need. (I would be a little anxious about the current-sharing abilities of the multiple output transistors' base resistors of just 0.1R but I'm sure it works very reliably).