340 Rear Main Seal ?

And I assume your crank had the knurling on the seal contact surface, right?
Yup...I'm assuming that is there to push the oil away from the seal (just a guess). I have not had an issue with this seal, however; I had my first ever rear main seal leak with this same gasket when I first built this engine....not sure how that happened, but after pulling the motor and changing out the seal it has been fine. This is motor # 7 for this car (I think), so not too bad to only have 1 leaker.