Or even fps differences in the ports.
Iron heads i have in the 280s are milled to 60cc and have about .028-.030 deep shallow sides cut for quench head clearance...and they're also a 186cc port
Bigger than eddy,speed,etc but a hair under trickflops...right in the range of a w2... but they're J heads.
I could possibly set that up with Richard and Dulcich. But I’d bet Dulcich already has some ported iron x heads he’s going to test. Doesn’t hurt to ask if they’re interested.