Verifying a 426 wedge

Numbers are in the same place on both engines... Front center pad above the water pump area for the Stampings. Side of block for the casting numbers. They will be different for each, meaning there are no common stamping or casting numbers between the two blocks. There are not visual differences between the two, they may well look identical other than the numbers, at least whilst still assembled.

Scroll down, to blocks....
A Guide To Mopar V8 Cylinder Head And Block Casting Numbers (enginelabs.com)

Also, if you can see the top pad stampings, you are gonna see 440 stamped on a 440, you will see 426 or just 42 if a 426 and you will see 41 if a 413.

HTH, Lefty71