Turner Reich Anastigmat elements - mix'n'match?

So this may or may not be another in my series of stupid questions, but I'll ask it anyway.

I just received a Turner Reich Anatigmat Series II 12/21/28" f/6.8 in a Betax 4 (the times need a CLA, but B and T are working, which is probably all I'll use at f/32-64 contact-printed 8x10" landscapes anyway).
Digging around, I've answered most of my initial questions from pages 2-4 of this catalogue.
So it's a Number 5, the Rear cell alone is 21" f/12, Front mounted in the rear is 28" f/16, and both together is 12" f/6.8.
Just having a guess, the formula: total = 1/((1/f)+(1/r)) seems to hold for both focal lengths and apertures.

Now, with this deal I also got two extra cells, both idental serial number, simply marked "Turner Reich" and "14 IN" or "18 IN".
These seem to be from the Convertible Anastigmat (set of 4) series described at the top of page 7, ie the 14/18/24/28" elements.
Having only the 14/18, together I can make the 8" f/6.4 combo as well.

So the question is, can I mix and match these two sets to make more combos? Are they the same elements as used on page 3, or totally different ones that don't mate?
ie, if they mate, then 14/21 gives 8.4", 14/28 gives 9.3", 18/21 gives 9.7", 18/28 gives 11".
They don't list the apertures for bare cells, but with 2 maths-based degrees you'd think I could figure them out by working backwards from the combos.

The one other thing I'm wondering about this second set is coverage, nowhere on p7 does it say anything about coverage or angle of view.
Assuming that the 4 cells are taken from the same series as on pages 2-4, there the 14" comes under #3, covering 5x7", and the 18" is from #4 covering 6x8", so am I right in assuming they won't cover 8x10 singly or in combo with 21 or 28?
(As always, the coverage depends on aperture and personal taste, but if anyone's tried any of these combos I'd appreciate any guidance without wasting too much 8x10 film...)