I would argue that if you are going to come out with a resource of this magnatude, you need all the data you can get to back it up.  It is the QP's (Qualified Person) responsinilty to look at all the data, use judgement to decide what can or can't be used.  I would also suggest, you would take the time to validate any historical information.  For instance, I saw a press release that BGM put out showing all the historical holes.  of those, how many where drilled under current management?  I don't care what age the DH is if done under current management, but it better be relevant or you are not managing your company properly.  The companies QP (the VP of Ex.) has a responsibility to maintain the drill hole data base, the assays, the QA/QC of the sampling, etc.