R3 Blocks or "XR" Racing Blocks??

Guys,

as I said, I am setting up another engine to about +850 HP's! I need an expert opinion on two types of blocks!

What is the best for my project, this:

http://www.hughesengines.com/TechArticles/1ritterracingsmallblocks.php

or this ....

http://chucker54.stores.yahoo.net/cairrraenbls4.html


Recalling that have to be iron Small Block, 9.560 "Deck Height!



Hug!