Regarding the software, as far as I can tell many Bacula users have converted successfully, and I think a new install creates the tables with InnoDB now.
Also, shame on me for not saying this is Ubuntu Server 14.04 running MySQL 5.5.
So what's the desire to convert? I suggest slow query log before wasting the time, because you've got way more RAM than needed for the task. I'd also suggest looking up some things to tune MySQL, perhaps give it more memory, as much as you can in fact.