Quote Originally Posted by Bob W
The steel in the sleeve is better than the cast iron block. I would use a block with 8 sleeves and not be worried.

Bob
Bob,I am not try to beat you up.
This will give you a couple of ideas.
If you are using two different types metal the expansion and contraction of the metals are different because of this combined with the 400's siamesed cylinders creating hot spots in a high hp application.
When we ran 400's 10+ years ago we had a few problems with ring seal on a sleeved cylinder more than one time.
With that being said you may be o.k. for low hp applications.
Before any one pipes in here and talks about alu. racing I have not forgotten about them.