Like I said, that’s disingenuous at best. I say that because what the casting number on the block says doesn‘t mean squat.
If I used a 4 inch crank in a 273, could I still call it a 273? Nope. Because that number (273) is Cubic Inch Displacement and if you change the bore or stroke or both it is no longer displacing 273 inches.
The X block has a 318 cast into it. At a 4.000 or 4.040 or 4.100 bore it no longer is 318 inches.
I get what he’s doing but he’s not being truthful.