Not sure if this will help much, but this is an original TIAC GT lense I bought recently and paid for as I thought the worth was to me.......
That being said, I know from being in the injection molding industry for over 40 years now, that each run of a product will have variations.
Not every setup is going to duplicate the previous one, and back when these were made, it was even less repeatable run to run.
And to be honest, if your lenses are in very good condition like mine are, I would price them accordingly if you truly want to let them go.
They are a "rare" commodity, and demand a decent price as such.
Rare being not many out there, if any, in NOS condition, and even fewer in good shape.
Bottom line, I am into both sides (PON and TIAC) for over $700.00 and worth it to me to be honest, because I will need them when I get one or the other GT to the point I want them to be perfect, I will have them safely tucked away in the basement.
Now, just to reach that point.