I don't know about the angler, but the cruiser of that vintage had a raised fiberglass floor over the cockpit.  A year or so older had a two part floor which could be removed.  Prior to 2005/6 the boats "floor" was generally the inner hull.
A built up floor would would not be a detriment.   I would not want a floor screwed to the inner aspect of the hull.  It could be laid in a sealant or adhesive and be fine.