Thanks for that big research effort.
If I can't get anything like an OEM sensor I will have to go down that aftermarket path.
I am probably reading 20 degrees + low right now, and if the aftermarket ones read 20 degrees high, I think I would prefer the low reading sensor just for the psychological benefit.
The style you posted with the long probe end is different from the "correct" OEM part, but I don't know if that is a relevant dimension regarding proper fitment.
I will poke around the web a bit more and see if I can scare up any interest on the part of any suppliers to do a physical inventory check. Considering how many 454s Mr. Goodwrench must have rebuilt, there must be a correct replacement sensor somewhere out there. I was hoping to find a NOS part somewhere but no such luck yet.