this is the best half dollar that i've found so far in my collection as far as a sharply detailed reverse is concerned.. my question is... would one consider this to be/have FBL?
Yes, that appears to be FBL. There is a small mark across the top set of lines at the far left, but I've seen worse in NGC holders as FBL. It absolutely meets the PCGS requirements. Of course, it appears to be AU so not worth submitting.
Ah, they weren't there at first. There is too much glare where the lines are for me to tell for sure.
FBL, but not worth slabbing. The scratch through the lines on the left hand side would have no affect on PCGS giving the coin an FBL as they only grade the lower set of lines, while NGC grades both the lower and upper set of lines. Further, both major TPG's don't really have a firm and fast policy when it comes to scratches through bell lines. Sometimes they will give FBL, sometimes they won't. Generally speaking, the more valuable the underlying coin is (date/mm etc.) the tougher they'll be on giving FBL if there is a scratch through the bell lines. 1955 is a common date, so it's much more likely NGC's graders would give it a FBL too.