Yea, PM7/P29 sit 1mm/.040" down on Z6/A6 bore.
dont take this the wrong way, but this is where you guys are getting it wrong. lol
with PM7 pistons, the deck height in
a D16a1 is .040
a D16a6 is .020
and a D16z6 is .000
the blocks are decked different.
on my d16a1's, i always deck them .040 for pm7's
and .020 on my d16a6's other than the one i'm running right now. it's was barely cut at .004 just to make sure it was flat, and i measured the deck on it, and it was .016
now if you use the almost flat top 86/87 d16a1 pistons in a z6 block, they will actually come out of the bore a lil bit because the tops sit higher than the pm7 pistons. that's why they only went from 9.3:1 cr in a 86/87 d16a1 to 9.5:1 cr in a 88/89 d16a1, even though the pm7 has a dome on it.

but yeah, i always have my engine builds machined and i always double check everything to be sure it's right.
