I can tell you that with an RPM head, 270’s are possible without the 2.05 valve or any chamber mods.
Pinch at .970 and some pretty “safe” bolt bulge shaping.
But……..it did get some worthwhile SSR work.
You know it, I know it, and anyone that has ported heads seriously knows it. The short side is where the gold is hidden. But I know it and you know that the short side scares the be-jebies out of everyone that tries their hand at porting so we couldn’t go there.