In a post elsewhere here was a comparison of a 454 Chevy, 455 Pontiac (longer stroke), 455 Olds, (longer stroke) and a stroker 451, 400 based.
The Mopar finished last, by a substantial margin. Why? Stock iron heads that flowed poorly compared to the others, probably 100 cfm less than the winning Chevy.
Building a stoker, without improving the heads is just silly, imho.