On my 470 I think I'll pick up 50 hp by switching from the 240 heads to the 270 heads but your mileage may vary. I'm right at sonic choke with the 240 heads on my engine so the larger intake port should allow the peak points to move up. But how far things will move all depends on how good the 270 heads actually work. Just making the inlets on the ports bigger may or may not work very well in practice. It all depends on how well the entire port works with the larger inlet.

I'm assuming that Trick Flow will start shipping the 270 heads after SEMA. If that is correct then I could be on the dyno by the end of the year. My 470 has 85 dyno pulls on it so we're pulling it apart and looking at the bearings. If everything looks good we'll put it back together and bolt on the 270 heads when they show up.