It could be done on a stock block... but probably not very reliably.
If I was going to try for that HP on a stock block for the street I would probably short fill the block and keep the bores as small as I possibly could, but it would be better full-filled and then you lose the streetability. Sonic check the bores for core shift & wall thickness. Good studs on the mains would be a must and I'd probably start with a 2-bolt block and install aftermarket billet steel splayed 4-bolt caps. Then cross my fingers and pray.
The stock block will also give up HP due to cylinder bore distortion & flex compared to an aftermarket block with thicker bores, and given the high cylinder pressures the thicker deck of an aftermarket block sure would be nice too.
As far as iron aftermarket blocks I like Dart & GM Bowtie. I don't think I'd recommend an aluminum block at that power level but Brodix is my aluminum block of choice.