I pulled my engine, 89 L98 350, along with the trans... In order to get my transmission rebuilt. So I decided to remove all the emissions hardware and install some headers. Well... as I removed the manifolds I snapped two bolts off into the head. Yay... so I pulled the heads so I could drill and extract the bolts at work.

Anyway I don't remember my other L98 having 4 valve reliefs like these pistons do. These are dished but they don't look familiar to me... are these stock? The head gaskets were Fel pro so that tells me this motor has been gone through at some point. It's really clean inside and everything looks great. So I'm going to toss in a LT4 hot cam, valve springs and new gaskets while leaving the rest the way it is....

The look like a stock piston or a stock replacement piston. Clean the tops off to see if there's an 030 stamped into them to suggest an overbore

you could also take a micrometer and measure the cylinder bore if it is 4.00" or somewhat close to that then its stock