Sm Blk heads

I've always heard that OEM Magnums flow a bit better that OEM LA heads while racing IHRA Stock in the crate motor classes. The 360/300hp Magnum was "refactored" 5hp more than the 360/300hp Commando LA combo. Here is a "rough" chart, but the quality of porting and valve jobs, as well as different flow benches, are a factor. They don't mention valve sizes in most cases, but the "stock" 894 and 915J are likely 2.02". Personally, I preferred the LA combo due to familiarity and parts availability.

I was also told that there were also 2 different OEM Magnum castings, with one being better than the other. But I don't know more than that.

Mopar LA Cylinder Head Comparison