I thought RCM sold the complete short block, but it doesn't look they do (see here).
Kris (RSS) is trying to get a deal with Subie Japan to get ahold of some, but he hasn't had any luck as yet.
I guess you could always ask Kris if he's willing to separate the heads from a short and send it to you (he has one sitting there at the moment; he also has one of his Option 1 engines ready to be delivered...)
So ive been told by Outfront Motorsport that with the ver 10 JDM block that the factory steel insert in the bore is the same in the Vers 10 jdm as it is in all the other 207's and only the alloy around it is thicker.!