Doesn't really matter what he tells you.  The California SoS website has the information you need for names of incorporators, directors, officers, shareholders (maybe not all of that, but it's a good start).  Date of incorporation and date of dissolution.  How do you even know your client is a corporation?  ("Just because he told me.")  And how do you know there was even an S election?  ("Just because . . .")

And when dealing with cannabis, it's usually an all-cash business.  I don't think that would change for a "lab."  I seem to recall this nomenclature was a way that dealers got around some of the regulations in the early days.  You're going to trust books kept for cash receipts and disbursements?  I wonder how many sets of books there are.  Maybe six -- one for each partner.