This thread got me to thinkin about it.
The only factory dish pistons I remember seeing were 428 pistons. Seems they had a small dish in the center, so they could run 400 heads.
So, for you guys who know, what other Pontiac V8 engines had factory dish pistons ?
Did some 421 engines have dish pistons, so they could run 389 heads ? No experience with 421 engines.