X-heads vs J-heads: what's the difference??

Thanks for the schooling ... and it was fast too!

Okay, so the X-head is the 68-70 big 2.02 valve head. The J-head was phased in sometime in 70 and for the 70-71 model years it too had the big 2.02 valves until 72 at which point the 1.88 valve was introduced. Finally, there is a minor difference in the combustion chamber volume between the two. Is that pretty much it in a nutshell?

Okay, apart from the valve size and combustion chamber volume, is there any differences in the port contours? One of the posters said that he thought that there was a difference in the bowl to port short-side radius (I don't think he specified if it was the intake, exhaust or both?). Any changes there that we know of?