Mopar R1 block

Guys above are correct.
The W5 is actually a “small head” for a 4 inch crank motor. That was more cubes than it was designed to be run on
I campaigned 422 forever with W5 heads. It wasnt all out combo, but ran 9.80’s in a 3350 pound car with super stock springs
I shifted it at 7 and trapped about 7400. Nice heads, if you find a set with integrity that wont leak, or ultimately leak.
Its very easy to run 9’s in a A body with them. If my car had been 3000 pounds it would have run 9.40’s/50’s. This with shelf headers and a cam that had very modest lobes because i drove it around a lot.
Probably little more on the table more aggressive lobe