The little 318 & Racer Brown's quality products

I have a 5.2 Magnum shortblock I have been thinking about building to replace a Slant Six in a 72 Demon.
A general consensus is to build a 5.9 or go big and stroke it. I already have 2 cars with mild 318 LA builds which are plenty fun but sometimes I feel the need to go with more, which honestly, I'm really trying to talk myself into it. Other times I want to rebuild and heavily modify the six. Looking at the cost though and seeing your post I see where I can get more with less and have decided to use what I have and build from there. Of course there are questions and the first is.
You mention "Stock pistons flipped" ...what do you mean by that?
Thanks