Mopar 413/426 Max Wedge block casting number confusion

The head gasket has some passages that are clogged with rust, that does not happen in a few miles
Also the gasket is only available NOS, research shows it was the correct gasket, by number for the 426
Unless someone pulled it down and bored it 60 over which I doubt, it would be a 426. The inside of the motor is very clean, and you can barely catch a fingernail on the cylinder ridge. When I pull it completely, the date codes on the bearings should help clarify as well as a Sonic check, 413 to 426 is .0060 over to make a 426, the walls I'm my block will be thin if it is a bored 413