What did you end up using to anchor the walls down?
Were the tapcons you mentioned actual tapcons or were you just using that as a generic term?
We used to use 'Wedgebolts' at work for securing unistrut to concrete floor, they really dug in good. I used them to hold some shelves on a cinder block wall later in my parents garage. Only thing in my limited experience that grabbed into cinder block securely and easy to use.