H405CP versus stock magnum 5.9 pistons

You need to be careful and dot your i's and cross your t's, because the Magnum blocks have a shorter deck height than the LA. I believe those 405s are actually for the LA, so make SURE you do the math before you buy.

Yep that's why I asked. I have learned not to trust catalogs and their specs. Fifteen years in the parts business was good for something.
If I recall from my days in tech school, compression height should be a measurement of the center of the pin to the highest part of the piston with deck height not having any bearing. If these is accurate though Ill still be about .020 below the deck.
But you and others are a hell of a lot more knowledgeable on this stuff than I am. I whit wrenching almost twenty years ago and have only started dabbling again the last three years.