my first engine rebuild (318) advises

Got and measured couple of pistons.

Both were down at 0.04'' =1mm
head gasget was 0.04''
valve reliefs are couple cc and stock head is about 68cc, haven't measured that yet.

So my old compression was about 8.4:1

So i am starting to think these pistons are from 69 318 or some aftermarket cheap, bit more compression than stock 1972 318.
i have to measure them soon as i get one out.

If they have compression distance of about 1.74 with kb 1.81 i sould get compression of about 9.5-9.8:1 depends on head gasget.