Few years ago I had some work done by "The best Mopar guy in the area". He decked a Slant block for me and prepped a 2.5 block as well as ordered parts for it. I told him to make sure to get the right pistons for the 2.5 because there was a change in pin height. (He had the old pistons)

When I assembled the Slant I found the head dowels had been milled off in the block.

When I started to assemble the 2.5 I put a rod/piston in and had about +.250" positive deck height. He'd ordered the wrong pistons.

Fortunately, he is out of business AFAIK.