Agreed, either something is lost in translation, or engine builder is not really a builder.

But even if they were relying 100% on 440 source for that information, the charts on 440 source's website are actually pretty accurate.

OP, take a look at the spreadsheet/chart for "400-512" on their website to give you an idea of what is required and what ballpark CR you will arrive at http://store.440source.com/Stroker-Kits/products/3/

A 512 with rpm heads and flat tops, even .015 or so in the hole, is going to be close to 11.5:1.

Attempting to "read between the lines", maybe this is what they're talking about:

440 source offers only one dish volume-24cc. If that doesn't work for you, then you'll be milling heads or buying new heads to arrive at the target CR. Maybe the real question is, should it be left alone at 9.7:1 or will it be worth it to mill the heads to 75cc and arrive at 10.6:1? Was that really the question?