Some Blue Label guns had large front takedown pins while some had milspec front takedown pins. Additionally, some of the milspec front takedown pin guns were factory drilled for the detent and spring, while others were not. The Blue Lable guns that have a large front takedown pin should have a lower with A2 reinforcements front and rear and a magazine fence, but with the leading edge of the fence milled back to allow for the larger takedown pin.
My blue label is a 6551 (Sporter Target model) with a small milspec pushpin, factory drilled for the detent/spring (but without it factory installed) and a sear block pinned only on the right side.
There may have been some Blue Label slab-side guns, but that is beyond the scope of my knowledge on the subject.
ETA: that is a great price on the rifle....enjoy it.