Need some advice on some cylinder head gaskets

850 is certainly doable but you’re going to run up against the strength limits of the block. I recommend not trying to find that limit. Don’t think of giving up power by limiting the compression ratio. Think of it as a safety margin to be able to run boost more efficiently. How bout we ask a couple of questions. What are your goals for this car? Race? Street? Trying to hit an ET target? Have you ever driven a car with 600-700-800hp? These are serious questions.