There is/was a fella on the B body site that went to town on porting the poly head on his build. Sorry I can’t remember his name. He was doing unusual stuff for his build. Custom domed pistons etc…
I hang out with Charlie Servedio in which you can copy and paste into the YouTube search bar to find him. When he ports a head for the first time (AKA a strange to him head) he sonic checks the head before grinding as to not break through.
He likes to say he likes a thick wall so it will not have issues in the future. IIRC, his number is .100 for thickness. But, it is better to speak with him on this.