"Found these on ebay, now I'm convinced that the box is not original."
Well, maybe, maybe not. If the box is "period correct", and of the proper size for your revolver, it still might be original, even if the label is not.
Sometimes an original label is removed or otherwise comes off (though rare) and is replaced with a non-factory label. While I thought the label on your box looked to be unoriginal, I couldn't see enough of the box to know if it was.
Your box looks to be a "five ringer." The metal clamps holding the corners of these boxes together have three, four, or five "rings", depending on the frame size of the revolver, and whether or not it was originally equipped with Target Stocks from the factory. Your Combat Magnum would have shipped in a "five ring" box (as a K-frame with Target Stocks as original equipment), so you have that going for you.
Most often, though, a nickel gun from your gun's era would ship in a grey box, whereas a blued gun would ship in a blue box, but this was not always the case.
We would need to see the top and bottom, and other end of your box (showing any other markings and/or factory imprinting) to be more helpful.