That establishes that the piston deck heights are different, says nada in itself about the block heights.
I agree that it would be a better way to go, but...........
Don't be so sure about the deck heights (because they're the same or maximum slight difference like 0,2 0,3mm). Have you ever saw the 8v and 16v pistons? If yes, you should know why they're good for decompression, and that's not deck height question...
8V - flat
16v - like a bath
Can't find better pics fast, but there should be a lot on the craib project.
By the way, in garage I have a 16v bottom end engine, and still got the old gasket. Also got a 8v old gasket, will make a comparison in next days.
For the part number, I think the main difference is the thickness, or material type, so different part numbers, but this don't mean that you can't switch them.
Better pics:
For the block oil or water holes difference, yep, it seem's that there are differences. I discovered some by looking opened munkul's engine.
The holes near pistons, the nearest, on 16v block are bigger than on 8v craigb engine.
Photos for comparison:
Craigb 8v block with mixed pistons in:
Munkul 188 16v block with decompression plate on it:
Munkul 188 16v block with head gasket only on it:
Another strange thing for me, very very strange, is that the decompression plate used by munkul covers one hole present on block and on the standard head gasket O_O
Low left angle, where's that diarrea spot

No hole on decomp plate, yes hole on block and head gasket. O_O But maybe it's better to open a separate topic for these block holes things
Low left angle, where's that diarrea spot there should be the smaller of these two holes.
(3 holes on one angle, and 2 on the other, on decomp plate we have 3 holes on one side, and 1 instead of two on the other O_O). The 8v block also has 3 + 1 instead of 3 + 2.
Another pic of Munkul's 188 16v block (this is 1.4):
I feel like a crazy investigator, but it's funny for me discover these things
