I have that 6'2" alt at 2 3/8 as well (and love it) and the figure I got from Nev a while back was 28.7 litres. I now really enjoy the MB at 29.9 but I also weigh in at close to 90kgs. It is only a 1 litre / 2.8% step in either direction for you so I guess while it won't matter too much, it depends how you feel on the Alt and whether you want a teeny tiny little more or less float. (MB weighs 168 and rides the thick 5'10" at 27.2 litres)
I'm finding that my MB covers anything I could surf the alt in (this model alt also has more rocker than the current version) but offers higher performance and response. Certainly it does go best in better waves.