Anybody break a stock block, if so at what hp?

im making ATLEAST 100hp more on nitrous then the 600hp limit with a stock 91 LA block that is half filled, stock caps and bolts. Motor sees 7200rpm every pass, oh and its a 4" arm engine...knock on wood maybe, but no issues so far. To be honest, I think the stock SB blocks are pretty tough- is an aftermarket block a better option, sure, but before being afraid about the block I would be afraid of that intake and the distribution issues it might cause when spraying, which could lead to some expensive bottom end breakage