Posted By:
Al C.risafulliWelcome, Dustin.
I think the best way to determine authenticity is to immerse yourself in the cards - both raw and graded - but to purchase them from reliable sources with good feedback in selling vintage cards. Once you've held a few dozen cards in your hand from a particular issue, it gets pretty easy to tell which ones are real and which ones aren't.
As a previous poster mentioned, the story you tell (lifelong collector, estate sale, selling them as reprints, etc.) is a classic story that people use to pawn off reprints by instilling just a tiny bit of hope that they're real. As you state, owning a few reprints is a good way to learn about what the reprints look like.
All is not lost, either. One time I bought a lot of about 30 cards like this, just so I could own the reprints, and when I received them it turned out that some of them were actual, real T206s - a few commons but also a few minor HOFers like Joss and Bresnahan. So maybe you'll luck out the same way.
Good luck!
-Al