Sorry for my absence.
Anyway, I should have mentioned that both taking lens sets are Yashinons, not Yashikors or Lumaxars. My viewing lenses are 80mm Yashinon f/2.8's , and I'm not mucking with that!
I have the rear EM cell already screwed in, same threading and pitch. I'm hoping I won't have to shim anything, the only thing that is unsettling is that the EM taking rear cell is almost twice the length screwhousing wise, and and probably more glass (I'm not sure.). I'm hoping that someone has done this before and knows of the results. But for tonight, I'm matching both front and rear EM cells, I'm not ready for potential weirdness.
It's kind of amazing what difference 4 years can make in specifications.