Basic economic theory states that the value of anything is exactly equal to what someone is willing to pay for it.
An original stock knucklehead in excellent condition is probably worth more to a collector than the price of a new reproduction model.
However I doubt that anyone would give me the price of a new repo for my '47 chopped bike.
Also the person who wants an original bike probably has different values than the person who would buy a repo.
Therefore I don't think the value of the repo will have any signifigant effect on the value of the originals.