Anybody recognize these 340 pistons?

The web site clearly says 68-71 and I have ran in to this before , it is not a 68-71 replacement , have fun trying to find cast 68-71 replacements for that matter, The site is wrong with the info and picture and I did read the thread and link. I am not here to miss inform anyone and have a pretty good knowledge of these engines!

What is the compression height of these pistons, then?

Without the OP measuring what he has, it's all speculation.